@article {pmid38466860, year = {2024}, author = {Xu, X}, title = {Inferring aerial behavior in Mesozoic dinosaurs: Implications and uncertainties.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {121}, number = {12}, pages = {e2401482121}, doi = {10.1073/pnas.2401482121}, pmid = {38466860}, issn = {1091-6490}, support = {42288201//The National Natural Science Foundation of China/ ; 202305AB350006//Yunnan Revitalization Talent Support Program/ ; }, mesh = {Animals ; *Dinosaurs ; Feathers ; Uncertainty ; }, } @article {pmid38346196, year = {2024}, author = {Kiat, Y and O'Connor, JK}, title = {Functional constraints on the number and shape of flight feathers.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {121}, number = {8}, pages = {e2306639121}, doi = {10.1073/pnas.2306639121}, pmid = {38346196}, issn = {1091-6490}, support = {NA//Field Museum (FMNH)/ ; NA//Zuckerman STEM/ ; }, abstract = {As a fundamental ecological aspect of most organisms, locomotor function significantly constrains morphology. At the same time, the evolution of novel locomotor abilities has produced dramatic morphological transformations, initiating some of the most significant diversifications in life history. Despite significant new fossil evidence, it remains unclear whether volant locomotion had a single or multiple origins in pennaraptoran dinosaurs and the volant abilities of individual taxa are controversial. The evolution of powered flight in modern birds involved exaptation of feathered surfaces extending off the limbs and tail yet most studies concerning flight potential in pennaraptorans do not account for the structure and morphology of the wing feathers themselves. Analysis of the number and shape of remex and rectrix feathers across a large dataset of extant birds indicates that the number of remiges and rectrices and the degree of primary vane asymmetry strongly correlate with locomotor ability revealing important functional constraints. Among these traits, phenotypic flexibility varies reflected by the different rates at which morphological changes evolve, such that some traits reflect the ancestral condition, whereas others reflect current locomotor function. While Mesozoic birds and Microraptor have remex morphologies consistent with extant volant birds, that of anchiornithines deviate significantly providing strong evidence this clade was not volant. The results of these analyses support a single origin of dinosaurian flight and indicate the early stages of feathered wing evolution are not sampled by the currently available fossil record.}, } @article {pmid38272887, year = {2024}, author = {Park, J and Son, M and Park, J and Bang, SY and Ha, J and Moon, H and Lee, YN and Lee, SI and Jablonski, PG}, title = {Escape behaviors in prey and the evolution of pennaceous plumage in dinosaurs.}, journal = {Scientific reports}, volume = {14}, number = {1}, pages = {549}, pmid = {38272887}, issn = {2045-2322}, support = {2022R1A6A3A01085943//National Research Foundation of Korea grant/ ; 2022R1I1A2060919//National Research Foundation of Korea grant/ ; RS-2023-00247087//National Research Foundation of Korea grant/ ; 2019R1A2C1004300//National Research Foundation of Korea grant/ ; Convergence grant 2019-2020//Seoul National University/ ; DGIST R&D Program (22-BRP-03)//Ministry of Science and ICT, South Korea/ ; }, abstract = {Numerous non-avian dinosaurs possessed pennaceous feathers on their forelimbs (proto-wings) and tail. Their functions remain unclear. We propose that these pennaceous feathers were used in displays to flush hiding prey through stimulation of sensory-neural escape pathways in prey, allowing the dinosaurs to pursue the flushed prey. We evaluated the escape behavior of grasshoppers to hypothetical visual flush-displays by a robotic dinosaur, and we recorded neurophysiological responses of grasshoppers' escape pathway to computer animations of the hypothetical flush-displays by dinosaurs. We show that the prey of dinosaurs would have fled more often when proto-wings were present, especially distally and with contrasting patterns, and when caudal plumage, especially of a large area, was used during the hypothetical flush-displays. The reinforcing loop between flush and pursue functions could have contributed to the evolution of larger and stiffer feathers for faster running, maneuverability, and stronger flush-displays, promoting foraging based on the flush-pursue strategy. The flush-pursue hypothesis can explain the presence and distribution of the pennaceous feathers, plumage color contrasts, as well as a number of other features observed in early pennaraptorans. This scenario highlights that sensory-neural processes underlying prey's antipredatory reactions may contribute to the origin of major evolutionary innovations in predators.}, } @article {pmid38190932, year = {2024}, author = {Dhouailly, D}, title = {The avian ectodermal default competence to make feathers.}, journal = {Developmental biology}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.ydbio.2024.01.002}, pmid = {38190932}, issn = {1095-564X}, abstract = {Feathers originate as protofeathers before birds, in pterosaurs and basal dinosaurs. What characterizes a feather is not only its outgrowth, but its barb cells differentiation and a set of beta-corneous proteins. Reticula appear concomitantly with feathers, as small bumps on plantar skin, made only of keratins. Avian scales, with their own set of beta-corneous proteins, appear more recently than feathers on the shank, and only in some species. In the chick embryo, when feather placodes form, all the non-feather areas of the integument are already specified. Among them, midventral apterium, cornea, reticula, and scale morphogenesis appear to be driven by negative regulatory mechanisms, which modulate the inherited capacity of the avian ectoderm to form feathers. Successive dermal/epidermal interactions, initiated by the Wnt/β-catenin pathway, and involving principally Eda/Edar, BMP, FGF20 and Shh signaling, are responsible for the formation not only of feather, but also of scale placodes and reticula, with notable differences in the level of Shh, and probably FGF20 expressions. This sequence is a dynamic and labile process, the turning point being the FGF20 expression by the placode. This epidermal signal endows its associated dermis with the memory to aggregate and to stimulate the morphogenesis that follows, involving even a re-initiation of the placode.}, } @article {pmid37886492, year = {2023}, author = {Li, WH and Chuong, CM and Chen, CK and Wu, P and Jiang, TX and Harn, HI and Liu, TY and Yu, Z and Lu, J and Chang, YM and Yue, Z and Lin, J and Vu, TD and Huang, TY and Ng, CS}, title = {Transition from natal downs to juvenile feathers: conserved regulatory switches in Neoaves.}, journal = {Research square}, volume = {}, number = {}, pages = {}, doi = {10.21203/rs.3.rs-3382427/v1}, pmid = {37886492}, abstract = {The transition from natal downs for heat conservation to juvenile feathers for simple flight is a remarkable environmental adaptation process in avian evolution. However, the underlying epigenetic mechanism for this primary feather transition is mostly unknown. Here we conducted time-ordered gene co-expression network construction, epigenetic analysis, and functional perturbations in developing feather follicles to elucidate four downy-juvenile feather transition events. We discovered that LEF1 works as a key hub of Wnt signaling to build rachis and converts radial downy to bilateral symmetry. Extracellular matrix reorganization leads to peripheral pulp formation, which mediates epithelial - mesenchymal interactions for branching morphogenesis. ACTA2 compartments dermal papilla stem cells for feather cycling. Novel usage of scale keratins strengthens feather sheath with SOX14 as the epigenetic regulator. We found this primary feather transition largely conserved in chicken (precocious) and zebra finch (altricial) and discussed the possibility that this evolutionary adaptation process started in feathered dinosaurs.}, } @article {pmid37735563, year = {2023}, author = {Slater, TS and Edwards, NP and Webb, SM and Zhang, F and McNamara, ME}, title = {Preservation of corneous β-proteins in Mesozoic feathers.}, journal = {Nature ecology & evolution}, volume = {}, number = {}, pages = {}, pmid = {37735563}, issn = {2397-334X}, support = {New Foundations//Irish Research Council (An Chomhairle um Thaighde in Éirinn)/ ; H2020-ERC-2014-StG-637691-ANICOLEVO//EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 European Research Council (H2020 Excellent Science - European Research Council)/ ; H2020-ERC-COG-101003293-Palaeochem//EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 European Research Council (H2020 Excellent Science - European Research Council)/ ; }, abstract = {Fossil proteins are valuable tools in evolutionary biology. Recent technological advances and better integration of experimental methods have confirmed the feasibility of biomolecular preservation in deep time, yielding new insights into the timing of key evolutionary transitions. Keratins (formerly α-keratins) and corneous β-proteins (CBPs, formerly β-keratins) are of particular interest as they define tissue structures that underpin fundamental physiological and ecological strategies and have the potential to inform on the molecular evolution of the vertebrate integument. Reports of CBPs in Mesozoic fossils, however, appear to conflict with experimental evidence for CBP degradation during fossilization. Further, the recent model for molecular modification of feather chemistry during the dinosaur-bird transition does not consider the relative preservation potential of different feather proteins. Here we use controlled taphonomic experiments coupled with infrared and sulfur X-ray spectroscopy to show that the dominant β-sheet structure of CBPs is progressively altered to α-helices with increasing temperature, suggesting that (α-)keratins and α-helices in fossil feathers are most likely artefacts of fossilization. Our analyses of fossil feathers shows that this process is independent of geological age, as even Cenozoic feathers can comprise primarily α-helices and disordered structures. Critically, our experiments show that feather CBPs can survive moderate thermal maturation. As predicted by our experiments, analyses of Mesozoic feathers confirm that evidence of feather CBPs can persist through deep time.}, } @article {pmid37515428, year = {2023}, author = {Urban, CA and Legendre, LJ and Clarke, JA}, title = {Description of natal down of the ostrich (Struthio camelus) and comparison with common quail (Coturnix coturnix): Developmental and evolutionary implications.}, journal = {Journal of anatomy}, volume = {}, number = {}, pages = {}, doi = {10.1111/joa.13936}, pmid = {37515428}, issn = {1469-7580}, support = {GT10473/HHMI/Howard Hughes Medical Institute/United States ; }, abstract = {Natal down is a feather stage that differs in both form and function from the definitive feathers of adult birds. It has a simpler structure that has been speculated to be similar to the body coverings of non-avian dinosaurs. However, inference of the evolution of natal down has been limited by our understanding of its structural variation in extant birds. Most descriptive work has focused on neognathous birds, limiting our knowledge of the full diversity of feathers in extant taxa. Here, we describe the natal down of a post-hatch ostrich (Struthio camelus) and compare it to that of a post-hatch quail (Coturnix coturnix). We confirm the presence of featherless spaces (apteria) in S. camelus and the lack of barbules on the tips of natal down in both species. We also find differences between dorsal and ventral natal down structures, such as barbule density in S. camelus and the extent of the bare portion of the barb in both species. Surprisingly, we do not find that the neoptiles of either species follow the ideal morphologies for increasing insulation. Finally, we hypothesize that the different barb types present in S. camelus natal down result from a large addition of new barb ridges during development, which is not known except in feathers with a rachis. These results have implications for our understanding of how structure informs function and development in understudied feather types, such as those shared by non-avian dinosaurs.}, } @article {pmid37400509, year = {2023}, author = {Kiat, Y and O'Connor, JK}, title = {Rarity of molt evidence in early pennaraptoran dinosaurs suggests annual molt evolved later among Neornithes.}, journal = {Communications biology}, volume = {6}, number = {1}, pages = {687}, pmid = {37400509}, issn = {2399-3642}, mesh = {Animals ; *Dinosaurs/anatomy & histology ; Phylogeny ; Molting ; Fossils ; Wings, Animal ; Birds ; }, abstract = {Feathers are a primitive trait among pennaraptoran dinosaurs, which today are represented by crown birds (Neornithes), the only clade of dinosaurs to survive the end Cretaceous mass extinction. Feathers are central to many important functions and therefore, maintaining plumage function is of great importance for survival. Thus, molt - by which new feathers are formed to replace old ones, is an essential process. Our limited knowledge regarding molt in early pennaraptoran evolution is based largely on a single Microraptor specimen. A survey of 92 feathered non-avian dinosaur and stem bird fossils did not find additional molting evidence. Due to its longer duration, in ornithological collections evidence of molt is found more frequently in extant bird species with sequential molts compared to those with more rapid simultaneous molts. The low frequency of molt occurrence among fossil specimens resembles collections of bird species with simultaneous molts. The dearth of molt evidence in the forelimbs of pennaraptoran specimens may have interesting implications regarding molt strategy during early avian evolution, and suggests that the yearly molting cycle may have evolved later, among crown birds.}, } @article {pmid37253379, year = {2023}, author = {Sathe, EA and Chronister, NJ and Dudley, R}, title = {Incipient wing flapping enhances aerial performance of a robotic paravian model.}, journal = {Bioinspiration & biomimetics}, volume = {18}, number = {4}, pages = {}, doi = {10.1088/1748-3190/acda03}, pmid = {37253379}, issn = {1748-3190}, mesh = {Animals ; *Flight, Animal ; *Robotic Surgical Procedures ; Wings, Animal/anatomy & histology ; Birds/anatomy & histology ; Mechanical Phenomena ; }, abstract = {The functional origins of bird flight remain unresolved despite a diversity of hypothesized selective factors. Fossil taxa phylogenetically intermediate between typical theropod dinosaurs and modern birds exhibit dense aggregations of feathers on their forelimbs, and the evolving morphologies and kinematic activational patterns of these structures could have progressively enhanced aerodynamic force production over time. However, biomechanical functionality of flapping in such transitional structures is unknown. We evaluated a robot inspired by paravian morphology to model the effects of incremental increases in wing length, wingbeat frequency, and stroke amplitude on aerial performance. From a launch height of 2.8 m, wing elongation most strongly influenced distance travelled and time aloft for all frequency-amplitude combinations, although increased frequency and amplitude also enhanced performance. Furthermore, we found interaction effects among these three parameters such that when the wings were long, higher values of either wingbeat frequency or stroke amplitude synergistically improved performance. For launches from a height of 5.0 m, the effects of these flapping parameters appear to diminish such that only flapping at the highest frequency (5.7 Hz) and amplitude (60°) significantly increased performance. Our results suggest that a gliding animal at the physical scale relevant to bird flight origins, and with transitional wings, can improve aerodynamic performance via rudimentary wing flapping at relatively low frequencies and amplitudes. Such gains in horizontal translation and time aloft, as those found in this study, are likely to be advantageous for any taxon that engages in aerial behavior for purposes of transit or escape. This study thus demonstrates aerodynamic benefits of transition from a gliding stage to full-scale wing flapping in paravian taxa.}, } @article {pmid37081273, year = {2023}, author = {}, title = {Amber reveals beetles with a fluffy diet: dinosaur feathers.}, journal = {Nature}, volume = {616}, number = {7958}, pages = {632}, pmid = {37081273}, issn = {1476-4687}, mesh = {Animals ; *Coleoptera ; *Dinosaurs/anatomy & histology ; Amber ; Feathers ; Diet/veterinary ; Fossils ; }, } @article {pmid37068225, year = {2023}, author = {Peñalver, E and Peris, D and Álvarez-Parra, S and Grimaldi, DA and Arillo, A and Chiappe, L and Delclòs, X and Alcalá, L and Sanz, JL and Solórzano-Kraemer, MM and Pérez-de la Fuente, R}, title = {Symbiosis between Cretaceous dinosaurs and feather-feeding beetles.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {120}, number = {17}, pages = {e2217872120}, pmid = {37068225}, issn = {1091-6490}, mesh = {Animals ; *Dinosaurs/anatomy & histology ; Feathers/anatomy & histology ; *Coleoptera ; Symbiosis ; Amber ; Ecosystem ; Fossils ; Birds/anatomy & histology ; Biological Evolution ; Mammals ; }, abstract = {Extant terrestrial vertebrates, including birds, have a panoply of symbiotic relationships with many insects and arachnids, such as parasitism or mutualism. Yet, identifying arthropod-vertebrate symbioses in the fossil record has been based largely on indirect evidence; findings of direct association between arthropod guests and dinosaur host remains are exceedingly scarce. Here, we present direct and indirect evidence demonstrating that beetle larvae fed on feathers from an undetermined theropod host (avian or nonavian) 105 million y ago. An exceptional amber assemblage is reported of larval molts (exuviae) intimately associated with plumulaceous feather and other remains, as well as three additional amber pieces preserving isolated conspecific exuviae. Samples were found in the roughly coeval Spanish amber deposits of El Soplao, San Just, and Peñacerrada I. Integration of the morphological, systematic, and taphonomic data shows that the beetle larval exuviae, belonging to three developmental stages, are most consistent with skin/hide beetles (family Dermestidae), an ecologically important group with extant keratophagous species that commonly inhabit bird and mammal nests. These findings show that a symbiotic relationship involving keratophagy comparable to that of beetles and birds in current ecosystems existed between their Early Cretaceous relatives.}, } @article {pmid36823531, year = {2023}, author = {Uno, Y and Hirasawa, T}, title = {Origin of the propatagium in non-avian dinosaurs.}, journal = {Zoological letters}, volume = {9}, number = {1}, pages = {4}, pmid = {36823531}, issn = {2056-306X}, support = {17H06385//Japan Society for the Promotion of Science/ ; 19K04061//Japan Society for the Promotion of Science/ ; }, abstract = {Avian wings as organs for aerial locomotion are furnished with a highly specialized musculoskeletal system compared with the forelimbs of other tetrapod vertebrates. Among the specializations, the propatagium, which accompanies a skeletal muscle spanning between the shoulder and wrist on the leading edge of the wing, represents an evolutionary novelty established at a certain point in the lineage toward crown birds. However, because of the rarity of soft-tissue preservation in the fossil record, the evolutionary origin of the avian propatagium has remained elusive. Here we focus on articulated skeletons in the fossil record to show that angles of elbow joints in fossils are indicators of the propatagium in extant lineages of diapsids (crown birds and non-dinosaurian diapsids), and then use this relationship to narrow down the phylogenetic position acquiring the propatagium to the common ancestor of maniraptorans. Our analyses support the hypothesis that the preserved propatagium-like soft tissues in non-avian theropod dinosaurs (oviraptorosaurian Caudipteryx and dromaeosaurian Microraptor) are homologous with the avian propatagium, and indicate that all maniraptoran dinosaurs likely possessed the propatagium even before the origin of flight. On the other hand, the preserved angles of wrist joints in non-avian theropods are significantly greater than those in birds, suggesting that the avian interlocking wing-folding mechanism involving the ulna and radius had not fully evolved in non-avian theropods. Our study underscores that the avian wing was acquired through modifications of preexisting structures including the feather and propatagium.}, } @article {pmid36631657, year = {2023}, author = {Padian, K}, title = {25th anniversary of the first known feathered dinosaurs.}, journal = {Nature}, volume = {613}, number = {7943}, pages = {251-252}, pmid = {36631657}, issn = {1476-4687}, mesh = {Animals ; *Anniversaries and Special Events ; *Dinosaurs/anatomy & histology ; *Feathers ; *Fossils/history ; History, 20th Century ; }, } @article {pmid36375073, year = {2022}, author = {Pittman, M and Kaye, TG and Wang, X and Zheng, X and Dececchi, TA and Hartman, SA}, title = {Preserved soft anatomy confirms shoulder-powered upstroke of early theropod flyers, reveals enhanced early pygostylian upstroke, and explains early sternum loss.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {119}, number = {47}, pages = {e2205476119}, pmid = {36375073}, issn = {1091-6490}, mesh = {Animals ; *Shoulder/anatomy & histology ; *Dinosaurs/anatomy & histology ; Wings, Animal/physiology ; Birds/physiology ; Sternum/anatomy & histology ; Flight, Animal/physiology ; Fossils ; Biological Evolution ; }, abstract = {Anatomy of the first flying feathered dinosaurs, modern birds and crocodylians, proposes an ancestral flight system divided between shoulder and chest muscles, before the upstroke muscles migrated beneath the body. This ancestral flight system featured the dorsally positioned deltoids and supracoracoideus controlling the upstroke and the chest-bound pectoralis controlling the downstroke. Preserved soft anatomy is needed to contextualize the origin of the modern flight system, but this has remained elusive. Here we reveal the soft anatomy of the earliest theropod flyers preserved as residual skin chemistry covering the body and delimiting its margins. These data provide preserved soft anatomy that independently validate the ancestral theropod flight system. The heavily constructed shoulder and more weakly constructed chest in the early pygostylian Confuciusornis indicated by a preserved body profile, proposes the first upstroke-enhanced flight stroke. Slender ventral body profiles in the early-diverging birds Archaeopteryx and Anchiornis suggest habitual use of the pectoralis could not maintain the sternum through bone functional adaptations. Increased wing-assisted terrestrial locomotion potentially accelerated sternum loss through higher breathing requirements. Lower expected downstroke requirements in the early thermal soarer Sapeornis could have driven sternum loss through bone functional adaption, possibly encouraged by the higher breathing demands of a Confuciusornis-like upstroke. Both factors are supported by a slender ventral body profile. These data validate the ancestral shoulder/chest flight system and provide insights into novel upstroke-enhanced flight strokes and early sternum loss, filling important gaps in our understanding of the appearance of modern flight.}, } @article {pmid35625398, year = {2022}, author = {Tahoun, M and Engeser, M and Namasivayam, V and Sander, PM and Müller, CE}, title = {Chemistry and Analysis of Organic Compounds in Dinosaurs.}, journal = {Biology}, volume = {11}, number = {5}, pages = {}, pmid = {35625398}, issn = {2079-7737}, support = {FOR 2685//Deutsche Forschungsgemeinschaft/ ; }, abstract = {This review provides an overview of organic compounds detected in non-avian dinosaur fossils to date. This was enabled by the development of sensitive analytical techniques. Non-destructive methods and procedures restricted to the sample surface, e.g., light and electron microscopy, infrared (IR) and Raman spectroscopy, as well as more invasive approaches including liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), time-of-flight secondary ion mass spectrometry, and immunological methods were employed. Organic compounds detected in samples of dinosaur fossils include pigments (heme, biliverdin, protoporphyrin IX, melanin), and proteins, such as collagens and keratins. The origin and nature of the observed protein signals is, however, in some cases, controversially discussed. Molecular taphonomy approaches can support the development of suitable analytical methods to confirm reported findings and to identify further organic compounds in dinosaur and other fossils in the future. The chemical properties of the various organic compounds detected in dinosaurs, and the techniques utilized for the identification and analysis of each of the compounds will be discussed.}, } @article {pmid35446639, year = {2022}, author = {Ortega, RP}, title = {Pterosaurs were clad in colorful plumage.}, journal = {Science (New York, N.Y.)}, volume = {376}, number = {6591}, pages = {335}, doi = {10.1126/science.abq6110}, pmid = {35446639}, issn = {1095-9203}, mesh = {Animals ; *Dinosaurs/anatomy & histology ; Feathers ; *Fossils ; }, abstract = {Study suggests feathers arose-and were used for display-well before reign of dinosaurs.}, } @article {pmid35444308, year = {2022}, author = {Benton, MJ}, title = {A colourful view of the origin of dinosaur feathers.}, journal = {Nature}, volume = {604}, number = {7907}, pages = {630-631}, pmid = {35444308}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; *Dinosaurs/anatomy & histology ; *Feathers ; *Fossils ; Pigmentation ; }, } @article {pmid35444275, year = {2022}, author = {Cincotta, A and Nicolaï, M and Campos, HBN and McNamara, M and D'Alba, L and Shawkey, MD and Kischlat, EE and Yans, J and Carleer, R and Escuillié, F and Godefroit, P}, title = {Pterosaur melanosomes support signalling functions for early feathers.}, journal = {Nature}, volume = {604}, number = {7907}, pages = {684-688}, pmid = {35444275}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; *Dinosaurs/anatomy & histology ; *Feathers ; *Fossils ; *Melanosomes ; Pigmentation ; }, abstract = {Remarkably well-preserved soft tissues in Mesozoic fossils have yielded substantial insights into the evolution of feathers[1]. New evidence of branched feathers in pterosaurs suggests that feathers originated in the avemetatarsalian ancestor of pterosaurs and dinosaurs in the Early Triassic[2], but the homology of these pterosaur structures with feathers is controversial[3,4]. Reports of pterosaur feathers with homogeneous ovoid melanosome geometries[2,5] suggest that they exhibited limited variation in colour, supporting hypotheses that early feathers functioned primarily in thermoregulation[6]. Here we report the presence of diverse melanosome geometries in the skin and simple and branched feathers of a tapejarid pterosaur from the Early Cretaceous found in Brazil. The melanosomes form distinct populations in different feather types and the skin, a feature previously known only in theropod dinosaurs, including birds. These tissue-specific melanosome geometries in pterosaurs indicate that manipulation of feather colour-and thus functions of feathers in visual communication-has deep evolutionary origins. These features show that genetic regulation of melanosome chemistry and shape[7-9] was active early in feather evolution.}, } @article {pmid35241194, year = {2022}, author = {Chitimia-Dobler, L and Mans, BJ and Handschuh, S and Dunlop, JA}, title = {A remarkable assemblage of ticks from mid-Cretaceous Burmese amber.}, journal = {Parasitology}, volume = {149}, number = {6}, pages = {1-36}, pmid = {35241194}, issn = {1469-8161}, abstract = {Four fossil ticks (Arachnida: Parasitiformes: Ixodida) are described from mid-Cretaceous (ca. 100 Ma) Burmese amber of Myanmar. Ixodes antiquorum sp. nov. (Ixodidae) is the first Mesozoic record of Ixodes and the oldest representative of the most species-rich extant tick genus. Its affinities appear to lie with modern Australian forms, consistent with the hypothesis that Burmese amber hosted Gondwanan faunal elements. Even more remarkable is Khimaira fossus gen. et sp. nov. which combines a body resembling that of a soft tick (Argasidae) with a basis capitulum more like that of a hard tick (Ixodidae). We refer it to Khimairidae fam. nov. as a possible transitional form between the two main families of ticks alive today. Another member of the extinct Deinocrotonidae is described as Deinocroton copia sp. nov., while the first described adult female for Cornupalpatum burmanicum is associated with a dinosaur feather barb.}, } @article {pmid35225424, year = {2022}, author = {Akat, E and Yenmiş, M and Pombal, MA and Molist, P and Megías, M and Arman, S and Veselỳ, M and Anderson, R and Ayaz, D}, title = {Comparison of vertebrate skin structure at class level: A review.}, journal = {Anatomical record (Hoboken, N.J. : 2007)}, volume = {305}, number = {12}, pages = {3543-3608}, doi = {10.1002/ar.24908}, pmid = {35225424}, issn = {1932-8494}, mesh = {Animals ; *Biological Evolution ; *Dinosaurs/physiology ; Feathers/anatomy & histology ; Integumentary System/anatomy & histology/physiology ; Birds/anatomy & histology ; Mammals/anatomy & histology ; }, abstract = {The skin is a barrier between the internal and external environment of an organism. Depending on the species, it participates in multiple functions. The skin is the organ that holds the body together, covers and protects it, and provides communication with its environment. It is also the body's primary line of defense, especially for anamniotes. All vertebrates have multilayered skin composed of three main layers: the epidermis, the dermis, and the hypodermis. The vital mission of the integument in aquatic vertebrates is mucus secretion. Cornification began in apmhibians, improved in reptilians, and endured in avian and mammalian epidermis. The feather, the most ostentatious and functional structure of avian skin, evolved in the Mesozoic period. After the extinction of the dinosaurs, birds continued to diversify, followed by the enlargement, expansion, and diversification of mammals, which brings us to the most complicated skin organization of mammals with differing glands, cells, physiological pathways, and the evolution of hair. Throughout these radical changes, some features were preserved among classes such as basic dermal structure, pigment cell types, basic coloration genetics, and similar sensory features, which enable us to track the evolutionary path. The structural and physiological properties of the skin in all classes of vertebrates are presented. The purpose of this review is to go all the way back to the agnathans and follow the path step by step up to mammals to provide a comparative large and updated survey about vertebrate skin in terms of morphology, physiology, genetics, ecology, and immunology.}, } @article {pmid34991180, year = {2022}, author = {Hendrickx, C and Bell, PR and Pittman, M and Milner, ARC and Cuesta, E and O'Connor, J and Loewen, M and Currie, PJ and Mateus, O and Kaye, TG and Delcourt, R}, title = {Morphology and distribution of scales, dermal ossifications, and other non-feather integumentary structures in non-avialan theropod dinosaurs.}, journal = {Biological reviews of the Cambridge Philosophical Society}, volume = {97}, number = {3}, pages = {960-1004}, doi = {10.1111/brv.12829}, pmid = {34991180}, issn = {1469-185X}, mesh = {*Animal Scales ; Animals ; Biological Evolution ; Birds ; *Carcinoma, Squamous Cell ; *Dinosaurs/anatomy & histology ; Feathers/anatomy & histology ; Fossils ; Osteogenesis ; Phylogeny ; }, abstract = {Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non-feathered integumentary structures in non-avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non-averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non-scale bearing skin is found in the contentious tetanuran Sciurumimus, ornithomimosaurians (Ornithomimus) and possibly tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non-avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake-like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co-occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.}, } @article {pmid34844669, year = {2021}, author = {Álvarez-Parra, S and Pérez-de la Fuente, R and Peñalver, E and Barrón, E and Alcalá, L and Pérez-Cano, J and Martín-Closas, C and Trabelsi, K and Meléndez, N and López Del Valle, R and Lozano, RP and Peris, D and Rodrigo, A and Sarto I Monteys, V and Bueno-Cebollada, CA and Menor-Salván, C and Philippe, M and Sánchez-García, A and Peña-Kairath, C and Arillo, A and Espílez, E and Mampel, L and Delclòs, X}, title = {Dinosaur bonebed amber from an original swamp forest soil.}, journal = {eLife}, volume = {10}, number = {}, pages = {}, pmid = {34844669}, issn = {2050-084X}, mesh = {*Amber ; Animals ; Biodiversity ; *Dinosaurs ; Forests ; *Fossils ; Soil ; Spain ; Wetlands ; }, abstract = {Dinosaur bonebeds with amber content, yet scarce, offer a superior wealth and quality of data on ancient terrestrial ecosystems. However, the preserved palaeodiversity and/or taphonomic characteristics of these exceptional localities had hitherto limited their palaeobiological potential. Here, we describe the amber from the Lower Cretaceous dinosaur bonebed of Ariño (Teruel, Spain) using a multidisciplinary approach. Amber is found in both a root layer with amber strictly in situ and a litter layer mainly composed of aerial pieces unusually rich in bioinclusions, encompassing 11 insect orders, arachnids, and a few plant and vertebrate remains, including a feather. Additional palaeontological data-charophytes, palynomorphs, ostracods- are provided. Ariño arguably represents the most prolific and palaeobiologically diverse locality in which fossiliferous amber and a dinosaur bonebed have been found in association, and the only one known where the vast majority of the palaeontological assemblage suffered no or low-grade pre-burial transport. This has unlocked unprecedentedly complete and reliable palaeoecological data out of two complementary windows of preservation-the bonebed and the amber-from the same site.}, } @article {pmid34752760, year = {2021}, author = {Benton, MJ and Currie, PJ and Xu, X}, title = {A thing with feathers.}, journal = {Current biology : CB}, volume = {31}, number = {21}, pages = {R1406-R1409}, doi = {10.1016/j.cub.2021.09.064}, pmid = {34752760}, issn = {1879-0445}, mesh = {Animals ; Biological Evolution ; *Dinosaurs/anatomy & histology ; *Feathers ; Fossils ; }, abstract = {Michael Benton and colleagues reminisce about the discovery of Sinosauripteryx, the first feathered dinosaur.}, } @article {pmid34719783, year = {2022}, author = {Davis, SN and Clarke, JA}, title = {Estimating the distribution of carotenoid coloration in skin and integumentary structures of birds and extinct dinosaurs.}, journal = {Evolution; international journal of organic evolution}, volume = {76}, number = {1}, pages = {42-57}, doi = {10.1111/evo.14393}, pmid = {34719783}, issn = {1558-5646}, mesh = {Animals ; Birds ; Carotenoids/metabolism ; *Dinosaurs ; Feathers/metabolism ; Phylogeny ; Pigmentation ; }, abstract = {Carotenoids are pigments responsible for most bright yellow, red, and orange hues in birds. Their distribution has been investigated in avian plumage, but the evolution of their expression in skin and other integumentary structures has not been approached in detail. Here, we investigate the expression of carotenoid-consistent coloration across tissue types in all extant, nonpasserine species (n = 4022) and archelosaur outgroups in a phylogenetic framework. We collect dietary data for a subset of birds and investigate how dietary carotenoid intake may relate to carotenoid expression in various tissues. We find that carotenoid-consistent expression in skin or nonplumage keratin has a 50% probability of being present in the most recent common ancestor of Archosauria. Skin expression has a similar probability at the base of the avian crown clade, but plumage expression is unambiguously absent in that ancestor and shows hundreds of independent gains within nonpasserine neognaths, consistent with previous studies. Although our data do not support a strict sequence of tissue expression in nonpasserine birds, we find support that expression of carotenoid-consistent color in nonplumage integument structures might evolve in a correlated manner and feathers are rarely the only region of expression. Taxa with diets high in carotenoid content also show expression in more body regions and tissue types. Our results may inform targeted assays for carotenoids in tissues other than feathers, and expectations of these pigments in nonavian dinosaurs. In extinct groups, bare-skin regions and the rhamphotheca, especially in species with diets rich in plants, may express these pigments, which are not expected in feathers or feather homologues.}, } @article {pmid34663691, year = {2021}, author = {Pittman, M and Barlow, LA and Kaye, TG and Habib, MB}, title = {Pterosaurs evolved a muscular wing-body junction providing multifaceted flight performance benefits: Advanced aerodynamic smoothing, sophisticated wing root control, and wing force generation.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {118}, number = {44}, pages = {}, pmid = {34663691}, issn = {1091-6490}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology/physiology ; Flight, Animal/*physiology ; Fossils/*anatomy & histology ; Wings, Animal/*anatomy & histology/physiology ; }, abstract = {Pterosaurs were the first vertebrate flyers and lived for over 160 million years. However, aspects of their flight anatomy and flight performance remain unclear. Using laser-stimulated fluorescence, we observed direct soft tissue evidence of a wing root fairing in a pterosaur, a feature that smooths out the wing-body junction, reducing associated drag, as in modern aircraft and flying animals. Unlike bats and birds, the pterosaur wing root fairing was unique in being primarily made of muscle rather than fur or feathers. As a muscular feature, pterosaurs appear to have used their fairing to access further flight performance benefits through sophisticated control of their wing root and contributions to wing elevation and/or anterior wing motion during the flight stroke. This study underscores the value of using new instrumentation to fill knowledge gaps in pterosaur flight anatomy and evolution.}, } @article {pmid34534442, year = {2021}, author = {Wang, M and O'Connor, JK and Zhao, T and Pan, Y and Zheng, X and Wang, X and Zhou, Z}, title = {An Early Cretaceous enantiornithine bird with a pintail.}, journal = {Current biology : CB}, volume = {31}, number = {21}, pages = {4845-4852.e2}, doi = {10.1016/j.cub.2021.08.044}, pmid = {34534442}, issn = {1879-0445}, mesh = {Animals ; Biological Evolution ; *Birds/anatomy & histology ; *Dinosaurs/anatomy & histology ; Feathers ; Fossils ; Phylogeny ; }, abstract = {Enantiornithes are the most successful group of Mesozoic birds, arguably representing the first global avian radiation,[1-4] and commonly resolved as the sister to the Ornithuromorpha, the clade within which all living birds are nested.[1][,][3] The wealth of fossils makes it feasible to comparatively test evolutionary hypotheses about the pattern and mode of eco-morphological diversity of these sister clades that co-existed for approximately 65 Ma. Here, we report a new Early Cretaceous enantiornithine, Yuanchuavis kompsosoura gen. et. sp. nov., with a rectricial fan combined with an elongate central pair of fully pennaceous rachis-dominated plumes, constituting a new tail plumage previously unknown among nonavialan dinosaurs and Mesozoic birds but which strongly resembles the pintail in many neornithines. The extravagant but aerodynamically costly long central plumes, as an honest signal of quality, likely evolved in enantiornithines through the handicap process of sexual selection. The contrasting tail morphotypes observed between enantiornithines and early ornithuromorphs reflect the complex interplay between sexual and natural selections and indicate that each lineage experienced unique pressures reflecting ecological differences. As in neornithines, early avialans repeatedly evolved extravagant structures highlighting the importance of sexual selection in shaping the plumage of feathered dinosaurs, even early in their evolutionary history.}, } @article {pmid34162868, year = {2021}, author = {Wang, M and Stidham, TA and Li, Z and Xu, X and Zhou, Z}, title = {Cretaceous bird with dinosaur skull sheds light on avian cranial evolution.}, journal = {Nature communications}, volume = {12}, number = {1}, pages = {3890}, pmid = {34162868}, issn = {2041-1723}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Bone and Bones/anatomy & histology ; China ; Dinosaurs/*anatomy & histology ; Feathers/anatomy & histology ; *Fossils ; Skull/*anatomy & histology ; }, abstract = {The transformation of the bird skull from an ancestral akinetic, heavy, and toothed dinosaurian morphology to a highly derived, lightweight, edentulous, and kinetic skull is an innovation as significant as powered flight and feathers. Our understanding of evolutionary assembly of the modern form and function of avian cranium has been impeded by the rarity of early bird fossils with well-preserved skulls. Here, we describe a new enantiornithine bird from the Early Cretaceous of China that preserves a nearly complete skull including the palatal elements, exposing the components of cranial kinesis. Our three-dimensional reconstruction of the entire enantiornithine skull demonstrates that this bird has an akinetic skull indicated by the unexpected retention of the plesiomorphic dinosaurian palate and diapsid temporal configurations, capped with a derived avialan rostrum and cranial roof, highlighting the highly modular and mosaic evolution of the avialan skull.}, } @article {pmid33905690, year = {2021}, author = {Pittman, M and Habib, MB and Dececchi, TA and Larsson, HCE and Pei, R and Kaye, TG and Norell, MA and Brusatte, SL and Xu, X}, title = {Response to Serrano and Chiappe.}, journal = {Current biology : CB}, volume = {31}, number = {8}, pages = {R372-R373}, doi = {10.1016/j.cub.2021.03.059}, pmid = {33905690}, issn = {1879-0445}, mesh = {*Fossils ; *Sports ; }, abstract = {In the recent study in Current Biology by Pei and colleagues[1], we used two proxies - wing loading and specific lift - to reconstruct powered flight potential across the vaned feathered fossil pennaraptorans. The results recovered multiple origins of powered flight. We respectfully disagree with the criticism raised by Serrano and Chiappe[2] that wing loading and specific lift, used in sequence, fail to discriminate between powered flight and gliding. We will explain this in reference to our original conservative approach.}, } @article {pmid33905689, year = {2021}, author = {Serrano, FJ and Chiappe, LM}, title = {Independent origins of powered flight in paravian dinosaurs?.}, journal = {Current biology : CB}, volume = {31}, number = {8}, pages = {R370-R372}, doi = {10.1016/j.cub.2021.03.058}, pmid = {33905689}, issn = {1879-0445}, mesh = {Animals ; Biological Evolution ; Birds ; *Dinosaurs ; Phylogeny ; *Running ; }, abstract = {Feathered dinosaurs discovered during the last decades have illuminated the transition from land to air in these animals, underscoring a significant degree of experimentation in wing-assisted locomotion around the origin of birds. Such evolutionary experimentation led to lineages achieving either wing-assisted running, four-winged gliding, or membrane-winged gliding. Birds are widely accepted as the only dinosaur lineage that achieved powered flight, a key innovation for their evolutionary success. However, in a recent paper in Current Biology, Pei and colleagues[1] disputed this view. They concluded that three other lineages of paravian dinosaurs (those more closely related to birds than to oviraptorosaurs) - Unenlagiinae, Microraptorinae and Anchiornithinae - could have evolved powered flight independently. While we praise the detailed phylogenetic framework of Pei and colleagues[1] and welcome a new attempt to understand the onset of flight in dinosaurs, we here expose a set of arguments that significantly weaken their evidence supporting a multiple origin of powered flight. Specifically, we maintain that the two proxies used by Pei and colleagues[1] to assess powered flight potential in non-avian paravians - wing loading and specific lift - fail to discriminate between powered flight (thrust generated by flapping) and passive flight (gliding).}, } @article {pmid33674573, year = {2021}, author = {Grimaldi, DA and Vea, IM}, title = {Insects with 100 million-year-old dinosaur feathers are not ectoparasites.}, journal = {Nature communications}, volume = {12}, number = {1}, pages = {1469}, pmid = {33674573}, issn = {2041-1723}, mesh = {Amber ; Animals ; *Dinosaurs/anatomy & histology ; Feathers ; Fossils ; Insecta ; }, } @article {pmid33472049, year = {2021}, author = {Vinther, J and Nicholls, R and Kelly, DA}, title = {A cloacal opening in a non-avian dinosaur.}, journal = {Current biology : CB}, volume = {31}, number = {4}, pages = {R182-R183}, doi = {10.1016/j.cub.2020.12.039}, pmid = {33472049}, issn = {1879-0445}, mesh = {Animals ; Cloaca/*anatomy & histology ; Dinosaurs/*anatomy & histology ; *Fossils ; Pigmentation ; }, abstract = {The Frankfurt specimen of Psittacosaurus sp. (SMF R 4970) from the Early Cretaceous Jehol deposits of Liaoning (Figure S1) exhibits exceptional preservation of scale-clad integument[1]. Preservation of colour patterns and countershading allowed a detailed reconstruction of this individual's physical appearance. It was previously noted that the cloacal region was preserved[2], but its detailed anatomy was incorrectly reconstructed. We show here that the fine anatomy of the vent is remarkably well preserved and can be retrodeformed to illustrate its three-dimensional nature. The vent's scale anatomy and pigmentation are distinct from adjacent body regions, and although its anatomy does not reveal much information about the ecology, or sex, of this dinosaur, it suggests possible roles for visual and olfactory signalling.}, } @article {pmid33293660, year = {2020}, author = {Kaye, TG and Pittman, M and Wahl, WR}, title = {Archaeopteryx feather sheaths reveal sequential center-out flight-related molting strategy.}, journal = {Communications biology}, volume = {3}, number = {1}, pages = {745}, pmid = {33293660}, issn = {2399-3642}, mesh = {Animals ; Biological Evolution ; Birds/genetics/*physiology ; Feathers/*physiology ; Flight, Animal/*physiology ; *Fossils ; Molting/genetics/*physiology ; }, abstract = {Modern flying birds molt to replace old and worn feathers that inhibit flight performance, but its origins are unclear. We address this by presenting and evaluating a ~150 million year old record of molting in a feathered dinosaur from the early bird Archaeopteryx. Laser-Stimulated Fluorescence revealed feather sheaths that are otherwise invisible under white light. These are separated by one feather and are not in numerical sequential order and are mirrored in both wings. This indicates that a sequential center-out molting strategy was already present at the origins of flight, which is used in living falcons to preserve maximum flight performance. This strategy would have been a welcome advantage for early theropod flyers that had poor flight capabilities. This discovery provides important insights into how birds refined their early flight capabilities before the appearance of the keeled sternum, pygostyle and triosseal canal.}, } @article {pmid33202226, year = {2020}, author = {Ksepka, DT}, title = {Feathered dinosaurs.}, journal = {Current biology : CB}, volume = {30}, number = {22}, pages = {R1347-R1353}, doi = {10.1016/j.cub.2020.10.007}, pmid = {33202226}, issn = {1879-0445}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; Flight, Animal ; Fossils/anatomy & histology ; }, abstract = {Feathers are the most complex integumentary structures in the animal world. They come in a variety of forms, the most familiar of which are remiges (flight feathers). Flight feathers are composed of a central shaft made up of a hollow calamus (quill), which is inserted into the skin, and a more distal rachis. Hundreds of parallel barbs branch from the sides of the rachis. In turn, smaller hooked barbules branch off the barbs, allowing them to interlock in a tight zipper-like fashion to form vanes. Variations in rachis, barb and barbule morphology result in other feather types such as contour feathers, bristles and down feathers. Feathers have a remarkable array of functions - they form airfoils and elaborate display structures, they serve to camouflage and insulate, to generate and help detect sound, and even to disintegrate into powder to condition other feathers.}, } @article {pmid33199731, year = {2020}, author = {Álvarez-Parra, S and Delclòs, X and Solórzano-Kraemer, MM and Alcalá, L and Peñalver, E}, title = {Cretaceous amniote integuments recorded through a taphonomic process unique to resins.}, journal = {Scientific reports}, volume = {10}, number = {1}, pages = {19840}, pmid = {33199731}, issn = {2045-2322}, abstract = {Fossil records of vertebrate integuments are relatively common in both rocks, as compressions, and amber, as inclusions. The integument remains, mainly the Mesozoic ones, are of great interest due to the panoply of palaeobiological information they can provide. We describe two Spanish Cretaceous amber pieces that are of taphonomic importance, one bearing avian dinosaur feather remains and the other, mammalian hair. The preserved feather remains originated from an avian dinosaur resting in contact with a stalactite-shaped resin emission for the time it took for the fresh resin to harden. The second piece shows three hair strands recorded on a surface of desiccation, with the characteristic scale pattern exceptionally well preserved and the strands aligned together, which can be considered the record of a tuft. These assemblages were recorded through a rare biostratinomic process we call "pull off vestiture" that is different from the typical resin entrapment and embedding of organisms and biological remains, and unique to resins. The peculiarity of this process is supported by actualistic observations using sticky traps in Madagascar. Lastly, we reinterpret some exceptional records from the literature in the light of that process, thus bringing new insight to the taphonomic and palaeoecological understanding of the circumstances of their origins.}, } @article {pmid32999314, year = {2020}, author = {Carney, RM and Tischlinger, H and Shawkey, MD}, title = {Evidence corroborates identity of isolated fossil feather as a wing covert of Archaeopteryx.}, journal = {Scientific reports}, volume = {10}, number = {1}, pages = {15593}, pmid = {32999314}, issn = {2045-2322}, abstract = {The historic fossil feather from the Jurassic Solnhofen has played a pivotal but controversial role in our evolutionary understanding of dinosaurs and birds. Recently, a study confirmed the diagnostic morphology of the feather's original calamus, but nonetheless challenged the proposed identity as an Archaeopteryx covert. However, there are errors in the results and interpretations presented. Here we show that the feather is most likely an upper major primary covert, based on its long calamus (23.3% total length) and eight other anatomical attributes. Critically, this hypothesis is independently supported by evidence of similar primary coverts in multiple specimens of Archaeopteryx-including from the same fossil site and horizon as the isolated feather. We also provide additional insights, such as an updated colour reconstruction of the entire feather as matte black, with 90% probability. Given the isolated nature of the fossil feather, we can never know the anatomical and taxonomic provenance with 100% certainty. However, based on all available evidence, the most empirical and parsimonious conclusion is that this feather represents a primary covert from the ancient wing of Archaeopteryx.}, } @article {pmid32989267, year = {2020}, author = {Yang, Z and Jiang, B and McNamara, ME and Kearns, SL and Pittman, M and Kaye, TG and Orr, PJ and Xu, X and Benton, MJ}, title = {Reply to: No protofeathers on pterosaurs.}, journal = {Nature ecology & evolution}, volume = {4}, number = {12}, pages = {1592-1593}, pmid = {32989267}, issn = {2397-334X}, mesh = {Animals ; *Dinosaurs/anatomy & histology ; *Feathers ; Fossils ; Integumentary System ; }, } @article {pmid32989266, year = {2020}, author = {Unwin, DM and Martill, DM}, title = {No protofeathers on pterosaurs.}, journal = {Nature ecology & evolution}, volume = {4}, number = {12}, pages = {1590-1591}, pmid = {32989266}, issn = {2397-334X}, mesh = {Animals ; *Dinosaurs/anatomy & histology ; *Feathers ; Fossils ; Integumentary System ; }, } @article {pmid32794182, year = {2020}, author = {Klingler, JJ}, title = {The evolution of the pectoral extrinsic appendicular and infrahyoid musculature in theropods and its functional and behavioral importance.}, journal = {Journal of anatomy}, volume = {237}, number = {5}, pages = {870-889}, pmid = {32794182}, issn = {1469-7580}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Dinosaurs/*anatomy & histology ; Muscle, Skeletal/*anatomy & histology ; }, abstract = {Birds have lost and modified the musculature joining the pectoral girdle to the skull and hyoid, called the pectoral extrinsic appendicular and infrahyoid musculature. These muscles include the levator scapulae, sternomandibularis, sternohyoideus, episternocleidomastoideus, trapezius, and omohyoideus. As non-avian theropod dinosaurs are the closest relatives to birds, it is worth investigating what conditions they may have exhibited to learn when and how these muscles were lost or modified. Using extant phylogenetic bracketing, osteological correlates and non-osteological influences of these muscles are identified and discussed. Compsognathids and basal Maniraptoriformes were found to have been the likeliest transition points of a derived avian condition of losing or modifying these muscles. Increasing needs to control the feather tracts of the neck and shoulder, for insulation, display, or tightening/readjustment of the skin after dynamic neck movements may have been the selective force that drove some of these muscles to be modified into dermo-osseous muscles. The loss and modification of shoulder protractors created a more immobile girdle that would later be advantageous for flight in birds. The loss of the infrahyoid muscles freed the hyolarynx, trachea, and esophagus which may have aided in vocal tract filtering.}, } @article {pmid32763170, year = {2020}, author = {Pei, R and Pittman, M and Goloboff, PA and Dececchi, TA and Habib, MB and Kaye, TG and Larsson, HCE and Norell, MA and Brusatte, SL and Xu, X}, title = {Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds.}, journal = {Current biology : CB}, volume = {30}, number = {20}, pages = {4033-4046.e8}, doi = {10.1016/j.cub.2020.06.105}, pmid = {32763170}, issn = {1879-0445}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Dinosaurs/*anatomy & histology ; Flight, Animal/*physiology ; Fossils ; Phylogeny ; Wings, Animal/*anatomy & histology/physiology ; }, abstract = {Uncertainties in the phylogeny of birds (Avialae) and their closest relatives have impeded deeper understanding of early theropod flight. To help address this, we produced an updated evolutionary hypothesis through an automated analysis of the Theropod Working Group (TWiG) coelurosaurian phylogenetic data matrix. Our larger, more resolved, and better-evaluated TWiG-based hypothesis supports the grouping of dromaeosaurids + troodontids (Deinonychosauria) as the sister taxon to birds (Paraves) and the recovery of Anchiornithinae as the earliest diverging birds. Although the phylogeny will continue developing, our current results provide a pertinent opportunity to evaluate what we know about early theropod flight. With our results and available data for vaned feathered pennaraptorans, we estimate the potential for powered flight among early birds and their closest relatives. We did this by using an ancestral state reconstruction analysis calculating maximum and minimum estimates of two proxies of powered flight potential-wing loading and specific lift. These results confirm powered flight potential in early birds but its rarity among the ancestors of the closest avialan relatives (select unenlagiine and microraptorine dromaeosaurids). For the first time, we find a broad range of these ancestors neared the wing loading and specific lift thresholds indicative of powered flight potential. This suggests there was greater experimentation with wing-assisted locomotion before theropod flight evolved than previously appreciated. This study adds invaluable support for multiple origins of powered flight potential in theropods (≥3 times), which we now know was from ancestors already nearing associated thresholds, and provides a framework for its further study. VIDEO ABSTRACT.}, } @article {pmid32679101, year = {2020}, author = {Kiat, Y and Balaban, A and Sapir, N and O'Connor, JK and Wang, M and Xu, X}, title = {Sequential Molt in a Feathered Dinosaur and Implications for Early Paravian Ecology and Locomotion.}, journal = {Current biology : CB}, volume = {30}, number = {18}, pages = {3633-3638.e2}, doi = {10.1016/j.cub.2020.06.046}, pmid = {32679101}, issn = {1879-0445}, mesh = {Animals ; Dinosaurs/anatomy & histology/classification/*physiology ; *Ecosystem ; Feathers/anatomy & histology/*physiology ; Flight, Animal/*physiology ; Molting/*physiology ; Wings, Animal/anatomy & histology/*physiology ; }, abstract = {Feather molt is an important life-history process in birds, but little is known about its evolutionary history. Here, we report on the first fossilized evidence of sequential wing feather molt, a common strategy among extant birds, identified in the Early Cretaceous four-winged dromaeosaurid Microraptor. Analysis of wing feather molt patterns and ecological properties in extant birds imply that Microraptor maintained its flight ability throughout the entire annual cycle, including the molt period. Therefore, we conclude that flight was essential for either its daily foraging or escaping from predators. Our findings propose that the development of sequential molt is the outcome of evolutionary forces to maintain flight capability throughout the entire annual cycle in both extant birds and non-avialan paravian dinosaurs from 120 mya. VIDEO ABSTRACT.}, } @article {pmid32615225, year = {2020}, author = {Jagadeesan, Y and Meenakshisundaram, S and Saravanan, V and Balaiah, A}, title = {Sustainable production, biochemical and molecular characterization of thermo-and-solvent stable alkaline serine keratinase from novel Bacillus pumilus AR57 for promising poultry solid waste management.}, journal = {International journal of biological macromolecules}, volume = {163}, number = {}, pages = {135-146}, doi = {10.1016/j.ijbiomac.2020.06.219}, pmid = {32615225}, issn = {1879-0003}, mesh = {Alkalies/chemistry ; Amino Acids/analysis ; Animals ; Bacillus pumilus/classification/*enzymology/*genetics/growth & development ; Biochemical Phenomena ; Culture Media/chemistry ; Feathers/chemistry/metabolism ; Hydrogen-Ion Concentration ; Ions/chemistry ; Keratins/chemistry/metabolism ; Peptide Hydrolases/*biosynthesis/*chemistry/drug effects/isolation & purification ; Poultry ; Protease Inhibitors/pharmacology ; RNA, Ribosomal, 16S ; Serine Proteases/*biosynthesis/*chemistry/drug effects/isolation & purification ; Solid Waste ; Solvents/chemistry ; Surface-Active Agents/chemistry ; Temperature ; Waste Management/methods ; }, abstract = {The increasing amount of recalcitrant keratinous wastes generated from the poultry industry poses a serious threat to the environment. Keratinase have gained much attention to convert these wastes into valuable products. Ever since primitive feathers first appeared on dinosaurs, microorganisms have evolved to degrade this most recalcitrant keratin. In this study, we identified a promising keratinolytic bacterial strain for bioconversion of poultry solid wastes. A true keratinolytic bacterium was isolated from the slaughterhouse soil and was identified and designated as Bacillus pumilus AR57 by 16S rRNA sequencing. For enhanced keratinase production and rapid keratin degradation, the media components and substrate concentration were optimized through shake flask culture. White chicken feather (1% w/v) was found to be the good substrate concentration for high keratinase production when supplemented with simple medium ingredients. The biochemical characterization reveals astounding results which makes the B. pumilus AR57 keratinase as a novel and unique protease. Optimum activity of the crude enzyme was exhibited at pH 9 and 45 °C. The crude extracellular keratinase was characterized as thermo-and-solvent (DMSO) stable serine keratinase. Bacillus pumilus AR57 showed complete degradation (100%) of white chicken feather (1% w/v) within 18 h when incubated in modified minimal medium supplemented with DMSO (1% v/v) at 150 rpm at 37 °C. Keratinase from modified minimal medium supplemented with DMSO exhibits a half-life of 4 days. Whereas, keratinase from the modified minimal medium fortified with white chicken feather (1% w/v) was stable for 3 h only. Feather meal produced by B. pumilus AR57 was found to be rich in essential amino acids. Hence, we proposed B. pumilus AR57 as a potential candidate for the future application in eco-friendly bioconversion of poultry waste and the keratinase could play a pivotal role in the detergent industry. While feather meal may serve as an alternative to produce animal feed and biofertilizers.}, } @article {pmid32614075, year = {2020}, author = {Wang, S and Chang, WL and Zhang, Q and Ma, M and Yang, F and Zhuo, D and Hans, HI and Yang, R and Wu, P and Habib, M and Juan, WT and Chuong, CM}, title = {Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises.}, journal = {Evolution; international journal of organic evolution}, volume = {74}, number = {9}, pages = {2121-2133}, doi = {10.1111/evo.14051}, pmid = {32614075}, issn = {1558-5646}, support = {R01 AR060306/AR/NIAMS NIH HHS/United States ; AR60306/NH/NIH HHS/United States ; AR47364/NH/NIH HHS/United States ; LT000728/2018//Human Frontier Science Program/ ; }, mesh = {Animals ; *Biological Evolution ; Chickens/*anatomy & histology/growth & development ; Dinosaurs/*anatomy & histology/growth & development ; Feathers/anatomy & histology/*growth & development ; Fossils/*anatomy & histology ; *Morphogenesis ; }, abstract = {The rachises of extant feathers, composed of dense cortex and spongy internal medulla, are flexible and light, yet stiff enough to withstand the load required for flight, among other functions. Incomplete knowledge of early feathers prevents a full understanding of how cylindrical rachises have evolved. Bizarre feathers with unusually wide and flattened rachises, known as "rachis-dominated feathers" (RDFs), have been observed in fossil nonavian and avian theropods. Newly discovered RDFs embedded in early Late Cretaceous Burmese ambers (about 99 million year ago) suggest the unusually wide and flattened rachises mainly consist of a dorsal cortex, lacking a medulla and a ventral cortex. Coupled with findings on extant feather morphogenesis, known fossil RDFs were categorized into three morphotypes based on their rachidial configurations. For each morphotype, potential developmental scenarios were depicted by referring to the rachidial development in chickens, and relative stiffness of each morphotype was estimated through functional simulations. The results suggest rachises of RDFs are developmentally equivalent to a variety of immature stages of cylindrical rachises. Similar rachidial morphotypes documented in extant penguins suggest that the RDFs are not unique to Mesozoic theropods, although they are likely to have evolved independently in extant penguins.}, } @article {pmid32218481, year = {2020}, author = {Jasinski, SE and Sullivan, RM and Dodson, P}, title = {New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous.}, journal = {Scientific reports}, volume = {10}, number = {1}, pages = {5105}, pmid = {32218481}, issn = {2045-2322}, mesh = {Animals ; Behavior, Animal ; Biodiversity ; Biological Evolution ; Datasets as Topic ; *Dinosaurs/anatomy & histology/classification ; Feathers ; Fossils ; New Mexico ; Phylogeny ; }, abstract = {Dromaeosaurids (Theropoda: Dromaeosauridae), a group of dynamic, swift predators, have a sparse fossil record, particularly at the time of their extinction near the Cretaceous-Paleogene boundary. Here we report on a new dromaeosaurid, Dineobellator notohesperus, gen. and sp. nov., consisting of a partial skeleton from the Upper Cretaceous (Maastrichtian) of New Mexico, the first diagnostic dromaeosaurid to be recovered from the latest Cretaceous of the southern United States (southern Laramidia). The holotype includes elements of the skull, axial, and appendicular skeleton. The specimen reveals a host of morphologies that shed light on new behavioral attributes for these feathered dinosaurs. Unique features on its forelimbs suggest greater strength capabilities in flexion than the normal dromaeosaurid condition, in conjunction with a relatively tighter grip strength in the manual claws. Aspects of the caudal vertebrae suggest greater movement near the tail base, aiding in agility and predation. Phylogenetic analysis places Dineobellator within Velociraptorinae. Its phylogenetic position, along with that of other Maastrichtian taxa (Acheroraptor and Dakotaraptor), suggests dromaeosaurids were still diversifying at the end of the Cretaceous. Furthermore, its recovery as a second North American Maastrichtian velociraptorine suggests vicariance of North American velociraptorines after a dispersal event during the Campanian-Maastrichtian from Asia. Features of Dineobellator also imply that dromaeosaurids were active predators that occupied discrete ecological niches while living in the shadow of Tyrannosaurus rex, until the end of the dinosaurs' reign.}, } @article {pmid32141103, year = {2020}, author = {Voegele, KK and Ullmann, PV and Lamanna, MC and Lacovara, KJ}, title = {Appendicular myological reconstruction of the forelimb of the giant titanosaurian sauropod dinosaur Dreadnoughtus schrani.}, journal = {Journal of anatomy}, volume = {237}, number = {1}, pages = {133-154}, pmid = {32141103}, issn = {1469-7580}, mesh = {Animals ; Biological Evolution ; Dinosaurs/*anatomy & histology ; Forelimb/*anatomy & histology ; Fossils ; Osteology ; Phylogeny ; }, abstract = {Soft tissues are variably preserved in the fossil record with external tissues, such as skin and feathers, more frequently preserved than internal tissues (e.g. muscles). More commonly, soft tissues leave traces of their locations on bones and, for muscles, these clues can be used to reconstruct the musculature of extinct vertebrates, thereby enhancing our understanding of how these organisms moved and the evolution of their locomotor patterns. Herein we reconstruct the forelimb and shoulder girdle musculature of the giant titanosaurian sauropod Dreadnoughtus schrani based on observations of osteological correlates and dissections of taxa comprising the Extant Phylogenetic Bracket of non-avian dinosaurs (crocodilians and birds). Fossils of Dreadnoughtus exhibit remarkably well-preserved, well-developed, and extensive muscle scars. Furthermore, this taxon is significantly larger-bodied than any titanosaurian for which a myological reconstruction has previously been attempted, rendering this myological study highly informative for the clade. In total, 28 muscles were investigated in this study, for which 46 osteological correlates were identified; these osteological correlates allowed the reconstruction of 16 muscles on the basis of Level I or Level II inferences (i.e. not Level I' or Level II' inferences). Comparisons with other titanosaurians suggest widespread myological variation in the clade, although potential phylogenetic patterns are often obscured by fragmentary preservation, infrequent myological studies, and lack of consensus on the systematic position of many taxa. By identifying myological variations within the clade, we can begin to address specific evolutionary and biomechanical questions related to the locomotor evolution in these sauropods.}, } @article {pmid31943887, year = {2020}, author = {Poust, AW and Gao, C and Varricchio, DJ and Wu, J and Zhang, F}, title = {A new microraptorine theropod from the Jehol Biota and growth in early dromaeosaurids.}, journal = {Anatomical record (Hoboken, N.J. : 2007)}, volume = {303}, number = {4}, pages = {963-987}, doi = {10.1002/ar.24343}, pmid = {31943887}, issn = {1932-8494}, mesh = {Animals ; Biological Evolution ; China ; Dinosaurs/*anatomy & histology/growth & development ; Feathers/*anatomy & histology ; Fibula/*anatomy & histology/growth & development ; *Fossils ; Humerus/*anatomy & histology/growth & development ; Osteology ; Phylogeny ; Tibia/*anatomy & histology/growth & development ; }, abstract = {Fossils from the Jehol Group (Early Cretaceous, Liaoning Province, China) are integral to our understanding of Paraves, the clade of dinosaurs grouping dromaeosaurids, troodontids, and avialians, including living birds. However, many taxa are represented by specimens of unclear ontogenetic age. Without a more thorough understanding of ontogeny, evolutionary relationships and significance of character states within paravian dinosaurs may be obscured and our ability to infer their biology restricted. We describe a complete specimen of a new microraptorine dromaeosaur, Wulong bohaiensis gen. et sp. nov., from the geologically young Jiufotang Formation (Aptian) that helps solve this problem. Phylogenetic analysis recovers the specimen within a monophyletic Microraptorinae. Preserved in articulation on a single slab, the type specimen is small and exhibits osteological markers of immaturity identified in other archosaurs, such as bone texture and lack of fusion. To contextualize this signal, we histologically sampled the tibia, fibula, and humerus and compared them with new samples from the closely related and osteologically mature Sinornithosaurus. Histology shows both specimens to be young and still growing at death, indicating an age for the new dinosaur of about 1 year. The holotype possesses several feather types, including filamentous feathers, pennaceous primaries, and long rectrices, establishing that their growth preceded skeletal maturity and full adult size in some dromaeosaurids. Comparison of histology in the new taxon and Sinornithosaurus indicates that macroscopic signs of maturity developed after the first year, but before cessation of growth, demonstrating that nonhistological indicators of adulthood may be misleading when applied to dromaeosaurids. Anat Rec, 303:963-987, 2020. © 2020 American Association for Anatomy.}, } @article {pmid31911937, year = {2020}, author = {Rezende, EL and Bacigalupe, LD and Nespolo, RF and Bozinovic, F}, title = {Shrinking dinosaurs and the evolution of endothermy in birds.}, journal = {Science advances}, volume = {6}, number = {1}, pages = {eaaw4486}, pmid = {31911937}, issn = {2375-2548}, mesh = {Adaptation, Physiological ; Animals ; *Biological Evolution ; Birds/anatomy & histology/*physiology ; Body Size ; Body Temperature Regulation/*physiology ; Dinosaurs/anatomy & histology/*physiology ; Feathers/physiology ; Fossils/anatomy & histology ; Mammals ; Phylogeny ; Tooth/physiology ; }, abstract = {The evolution of endothermy represents a major transition in vertebrate history, yet how and why endothermy evolved in birds and mammals remains controversial. Here, we combine a heat transfer model with theropod body size data to reconstruct the evolution of metabolic rates along the bird stem lineage. Results suggest that a reduction in size constitutes the path of least resistance for endothermy to evolve, maximizing thermal niche expansion while obviating the costs of elevated energy requirements. In this scenario, metabolism would have increased with the miniaturization observed in the Early-Middle Jurassic (~180 to 170 million years ago), resulting in a gradient of metabolic levels in the theropod phylogeny. Whereas basal theropods would exhibit lower metabolic rates, more recent nonavian lineages were likely decent thermoregulators with elevated metabolism. These analyses provide a tentative temporal sequence of the key evolutionary transitions that resulted in the emergence of small, endothermic, feathered flying dinosaurs.}, } @article {pmid31825173, year = {2020}, author = {Chiappe, LM and Di, L and Serrano, FJ and Yuguang, Z and Meng, Q}, title = {Anatomy and Flight Performance of the Early Enantiornithine Bird Protopteryx fengningensis: Information from New Specimens of the Early Cretaceous Huajiying Formation of China.}, journal = {Anatomical record (Hoboken, N.J. : 2007)}, volume = {303}, number = {4}, pages = {716-731}, doi = {10.1002/ar.24322}, pmid = {31825173}, issn = {1932-8494}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Bone and Bones/*anatomy & histology ; China ; Flight, Animal/*physiology ; Fossils ; *Phylogeny ; }, abstract = {The Early Cretaceous (∼131 Million Years Ago) Protopteryx fengningensis is one of the oldest and most primitive enantiornithine birds; however, knowledge of its anatomy has largely been limited to the succinct description of two specimens (holotype and paratype). This study describes two new specimens of P. fengningensis preserving most of the skeleton and plumage, and it therefore adds significantly to understanding the morphology of this important species and the character evolution of enantiornithine birds. The well-preserved plumage of these specimens also affords a quantitative assessment of the flight performance of P. fengningensis. Our aerodynamic considerations indicate that this early enantiornithine was capable of intermittent flight (bounding or flap-gliding), thus marking the earliest occurrence of such energy-saving aerial strategy. Anat Rec, 303:716-731, 2020. © 2019 American Association for Anatomy.}, } @article {pmid31822675, year = {2019}, author = {Gao, T and Yin, X and Shih, C and Rasnitsyn, AP and Xu, X and Chen, S and Wang, C and Ren, D}, title = {New insects feeding on dinosaur feathers in mid-Cretaceous amber.}, journal = {Nature communications}, volume = {10}, number = {1}, pages = {5424}, pmid = {31822675}, issn = {2041-1723}, mesh = {*Amber ; Animals ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; *Feeding Behavior ; Insecta/classification/*physiology ; }, abstract = {Due to a lack of Mesozoic fossil records, the origins and early evolution of feather-feeding behaviors by insects are obscure. Here, we report ten nymph specimens of a new lineage of insect, Mesophthirus engeli gen et. sp. nov. within Mesophthiridae fam. nov. from the mid-Cretaceous (ca. 100 Mya) Myanmar (Burmese) amber. This new insect clade shows a series of ectoparasitic morphological characters such as tiny wingless body, head with strong chewing mouthparts, robust and short antennae having long setae, legs with only one single tarsal claw associated with two additional long setae, etc. Most significantly, these insects are preserved with partially damaged dinosaur feathers, the damage of which was probably made by these insects' integument-feeding behaviors. This finding demonstrates that feather-feeding behaviors of insects originated at least in mid-Cretaceous, accompanying the radiation of feathered dinosaurs including early birds.}, } @article {pmid31795849, year = {2019}, author = {Wang, X and Tang, HK and Clarke, JA}, title = {Flight, symmetry and barb angle evolution in the feathers of birds and other dinosaurs.}, journal = {Biology letters}, volume = {15}, number = {12}, pages = {20190622}, pmid = {31795849}, issn = {1744-957X}, mesh = {Animals ; Biological Evolution ; Birds ; *Dinosaurs ; Feathers ; Flight, Animal ; Fossils ; Phylogeny ; }, abstract = {There has been much discussion over whether basal birds (e.g. Archaeopteryx and Confuciusornis) exhibited active flight. A recent study of barb angles has suggested they likely could not but instead may have exhibited a gliding phase. Pennaceous primary flight feathers were proposed to show significant shifts in barb angle values of relevance to the inference of flight in these extinct taxa. However, evolutionary trends in the evolution of these barb angle traits in extant volant taxa were not analysed in a phylogenetic frame. Neither the ancestral crown avian condition nor the condition in outgroup dinosaurs with symmetrical feathers were assessed. Here, we expand the fossil sample and reanalyse these data in a phylogenetic frame. We show that extant taxa, including strong flyers (e.g. some songbirds), show convergence on trailing barb angles and barb angle asymmetry observed in Mesozoic taxa that were proposed not to be active fliers. Trailing barb angles in these Mesozoic taxa are similar to symmetrical feathers in outgroup dinosaurs, indicating that selective regimes acted to modify primarily the leading-edge barb angles. These trends inform dynamics in feather shape evolution and challenge the notion that barb angle and barb angle ratios in extant birds directly inform the reconstruction of function in extinct stem taxa.}, } @article {pmid31792276, year = {2019}, author = {Carroll, NR and Chiappe, LM and Bottjer, DJ}, title = {Mid-Cretaceous amber inclusions reveal morphogenesis of extinct rachis-dominated feathers.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {18108}, pmid = {31792276}, issn = {2045-2322}, abstract = {We describe three-dimensionally preserved feathers in mid-Cretaceous Burmese amber that share macro-morphological similarities (e.g., proportionally wide rachis with a "medial stripe") with lithic, two-dimensionally preserved rachis-dominated feathers, first recognized in the Jehol Biota. These feathers in amber reveal a unique ventrally concave and dorsoventrally thin rachis, and a dorsal groove (sometimes pigmented) that we identify as the "medial stripe" visible in many rachis-dominated rectrices of Mesozoic birds. The distally pennaceous portion of these feathers shows differentiated proximal and distal barbules, the latter with hooklets forming interlocking barbs. Micro-CT scans and transverse sections demonstrate the absence of histodifferentiated cortex and medullary pith of the rachis and barb rami. The highly differentiated barbules combined with the lack of obvious histodifferentiation of the barb rami or rachis suggests that these feathers could have been formed without the full suite and developmental interplay of intermediate filament alpha keratins and corneous beta-proteins that is employed in the cornification process of modern feathers. This study thus highlights how the development of these feathers might have differed from that of their modern counterparts, namely in the morphogenesis of the ventral components of the rachis and barb rami. We suggest that the concave ventral surface of the rachis of these Cretaceous feathers is not homologous with the ventral groove of modern rachises. Our study of these Burmese feathers also confirms previous claims, based on two-dimensional fossils, that they correspond to an extinct morphotype and it cautions about the common practice of extrapolating developmental aspects (and mechanical attributes) of modern feathers to those of stem birds (and their dinosaurian outgroups) because the latter need not to have developed through identical pathways.}, } @article {pmid31778655, year = {2019}, author = {Chang, WL and Wu, H and Chiu, YK and Wang, S and Jiang, TX and Luo, ZL and Lin, YC and Li, A and Hsu, JT and Huang, HL and Gu, HJ and Lin, TY and Yang, SM and Lee, TT and Lai, YC and Lei, M and Shie, MY and Yao, CT and Chen, YW and Tsai, JC and Shieh, SJ and Hwu, YK and Cheng, HC and Tang, PC and Hung, SC and Chen, CF and Habib, M and Widelitz, RB and Wu, P and Juan, WT and Chuong, CM}, title = {The Making of a Flight Feather: Bio-architectural Principles and Adaptation.}, journal = {Cell}, volume = {179}, number = {6}, pages = {1409-1423.e17}, pmid = {31778655}, issn = {1097-4172}, support = {R01 AR047364/AR/NIAMS NIH HHS/United States ; R01 AR060306/AR/NIAMS NIH HHS/United States ; R01 GM125322/GM/NIGMS NIH HHS/United States ; R37 AR060306/AR/NIAMS NIH HHS/United States ; }, mesh = {*Adaptation, Physiological ; Animals ; Biological Evolution ; Birds/anatomy & histology ; Cell Adhesion Molecules/metabolism ; Cytoskeleton/metabolism ; Dermis/anatomy & histology ; Feathers/*anatomy & histology/*physiology ; Flight, Animal/*physiology ; Stem Cells/cytology ; Time Factors ; Transcriptome/genetics ; Wnt Signaling Pathway/genetics ; }, abstract = {The evolution of flight in feathered dinosaurs and early birds over millions of years required flight feathers whose architecture features hierarchical branches. While barb-based feather forms were investigated, feather shafts and vanes are understudied. Here, we take a multi-disciplinary approach to study their molecular control and bio-architectural organizations. In rachidial ridges, epidermal progenitors generate cortex and medullary keratinocytes, guided by Bmp and transforming growth factor β (TGF-β) signaling that convert rachides into adaptable bilayer composite beams. In barb ridges, epidermal progenitors generate cylindrical, plate-, or hooklet-shaped barbule cells that form fluffy branches or pennaceous vanes, mediated by asymmetric cell junction and keratin expression. Transcriptome analyses and functional studies show anterior-posterior Wnt2b signaling within the dermal papilla controls barbule cell fates with spatiotemporal collinearity. Quantitative bio-physical analyses of feathers from birds with different flight characteristics and feathers in Burmese amber reveal how multi-dimensional functionality can be achieved and may inspire future composite material designs. VIDEO ABSTRACT.}, } @article {pmid31538399, year = {2020}, author = {Roy, A and Pittman, M and Saitta, ET and Kaye, TG and Xu, X}, title = {Recent advances in amniote palaeocolour reconstruction and a framework for future research.}, journal = {Biological reviews of the Cambridge Philosophical Society}, volume = {95}, number = {1}, pages = {22-50}, pmid = {31538399}, issn = {1469-185X}, support = {//Faculty of Science/ ; //HKU MOOC course on Dinosaur Ecosystems/ ; HKPF PF16-09281//Hong Kong PhD Fellowship/ ; }, abstract = {Preserved melanin pigments have been discovered in fossilised integumentary appendages of several amniote lineages (fishes, frogs, snakes, marine reptiles, non-avialan dinosaurs, birds, and mammals) excavated from lagerstätten across the globe. Melanisation is a leading factor in organic integument preservation in these fossils. Melanin in extant vertebrates is typically stored in rod- to sphere-shaped, lysosome-derived, membrane-bound vesicles called melanosomes. Black, dark brown, and grey colours are produced by eumelanin, and reddish-brown colours are produced by phaeomelanin. Specific morphotypes and nanostructural arrangements of melanosomes and their relation to the keratin matrix in integumentary appendages create the so-called 'structural colours'. Reconstruction of colour patterns in ancient animals has opened an exciting new avenue for studying their life, behaviour and ecology. Modern relationships between the shape, arrangement, and size of avian melanosomes, melanin chemistry, and feather colour have been applied to reconstruct the hues and colour patterns of isolated feathers and plumages of the dinosaurs Anchiornis, Sinosauropteryx, and Microraptor in seminal papers that initiated the field of palaeocolour reconstruction. Since then, further research has identified countershading camouflage patterns, and informed subsequent predictions on the ecology and behaviour of these extinct animals. However, palaeocolour reconstruction remains a nascent field, and current approaches have considerable potential for further refinement, standardisation, and expansion. This includes detailed study of non-melanic pigments that might be preserved in fossilised integuments. A common issue among existing palaeocolour studies is the lack of contextualisation of different lines of evidence and the wide variety of techniques currently employed. To that end, this review focused on fossil amniotes: (i) produces an overarching framework that appropriately reconstructs palaeocolour by accounting for the chemical signatures of various pigments, morphology and local arrangement of pigment-bearing vesicles, pigment concentration, macroscopic colour patterns, and taphonomy; (ii) provides background context for the evolution of colour-producing mechanisms; and (iii) encourages future efforts in palaeocolour reconstructions particularly of less-studied groups such as non-dinosaur archosaurs and non-archosaur amniotes.}, } @article {pmid31497925, year = {2020}, author = {Currie, PJ and Evans, DC}, title = {Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta.}, journal = {Anatomical record (Hoboken, N.J. : 2007)}, volume = {303}, number = {4}, pages = {691-715}, doi = {10.1002/ar.24241}, pmid = {31497925}, issn = {1932-8494}, mesh = {Alberta ; Animals ; Dinosaurs/*anatomy & histology ; Fossils ; Phylogeny ; Skull/*anatomy & histology ; Tooth/anatomy & histology ; }, abstract = {The holotype of the dromaeosaurid Saurornitholestes langstoni was described in 1978 on the basis of fewer than 30 associated cranial and postcranial bones of a single individual from Dinosaur Provincial Park. Four additional partial skeletons of Saurornitholestes were recovered from Campanian (Upper Cretaceous) beds of Alberta and Montana over the next 25 years, although reasonably complete skeletons remained elusive, and virtually nothing was known about the skull. The lack of truly diagnostic material has been problematic, and the relationships of Saurornitholestes to other dromaeosaurids have been difficult to resolve because of the incomplete knowledge of its anatomy. In 2014, an almost complete skeleton, including the skull, was collected less than a kilometer from where the holotype had been found. Although similar in body size to Velociraptor, the facial region of the skull is relatively shorter, taller, and wider. The nasals are pneumatic. The premaxillary teeth are distinctive, and teeth previously identified in the Dinosaur Park Formation as Zapsalis abradens can now be identified as the second premaxillary tooth of S. langstoni. Morphology and wear patterns suggest that these may have been specialized for preening feathers. Many traits define a Campanian North American clade, Saurornitholestinae, that is distinct from an Asian clade that includes Velociraptor (Velociraptorinae). This new information on the skull allows a more complete evaluation of its systematic position within the Dromaeosauridae and supports the suggestion of at least two major faunal interchanges between Asia and North America during the Cretaceous. Anat Rec, 303:691-715, 2020. © 2019 American Association for Anatomy.}, } @article {pmid31359437, year = {2019}, author = {Persons, WS and Currie, PJ}, title = {Feather evolution exemplifies sexually selected bridges across the adaptive landscape.}, journal = {Evolution; international journal of organic evolution}, volume = {73}, number = {9}, pages = {1686-1694}, doi = {10.1111/evo.13795}, pmid = {31359437}, issn = {1558-5646}, mesh = {Animals ; *Biological Evolution ; Birds/*physiology ; Dinosaurs/*physiology ; Environment ; Feathers/*physiology ; Female ; Fossils ; Male ; Mutation ; Paleontology ; Phenotype ; Phylogeny ; *Selection, Genetic ; Sex Factors ; }, abstract = {Over the last two decades, paleontologists have pieced together the early evolutionary history of feathers. Simple hair-like feathers served as insulating pelage, but the first feathers with complex branching structures and a plainer form evolved for the purpose of sexual display. The evolution of these complex display feathers was essential to the later evolution of flight. Feathers illustrate how sexual selection can generate complex novel phenotypes, which are then available for natural selection to modify and direct toward novel functions. In the longstanding metaphor of the adaptive landscape, sexual selection is a means by which lineages resting on one adaptive peak may gradually bridge a gap to another peak, without the landscape itself being first altered by environmental changes.}, } @article {pmid31303494, year = {2019}, author = {O'Connor, J and Zheng, X and Dong, L and Wang, X and Wang, Y and Zhang, X and Zhou, Z}, title = {Microraptor with Ingested Lizard Suggests Non-specialized Digestive Function.}, journal = {Current biology : CB}, volume = {29}, number = {14}, pages = {2423-2429.e2}, doi = {10.1016/j.cub.2019.06.020}, pmid = {31303494}, issn = {1879-0445}, mesh = {Animal Nutritional Physiological Phenomena ; Animals ; *Diet ; *Digestion ; Dinosaurs/*physiology ; *Food Chain ; *Lizards ; }, abstract = {Direct indicators of diet and predator-prey relationships are exceedingly rare in the fossil record [1, 2]. However, it is through such traces that we can best understand trophic interactions in ancient ecosystems [3], confirm dietary inferences derived from skeletal morphologies [4], and clarify behavioral and ecological interpretations [5]. Here, we identify a previously unrecognized lizard species in the abdomen of a specimen of Microraptor zhaoianus, a small, volant dromaeosaurid (Paraves) with asymmetrical flight feathers on both its forelimbs and hindlimbs from the Early Cretaceous Jehol Biota [6-8]. The lizard is largely complete and articulated, confirming the current perception of Microraptor as an agile opportunistic predator that, like extant reptiles, including raptorial birds, ingested small prey whole and head first [9]. The lizard can be readily distinguished from previously recognized Early Cretaceous species based on its unusual widely spaced and brachydont dentition. Phylogenetic analysis suggests Indrasaurus wangi gen. et sp. nov. is a basal scleroglossan closely related to the slightly older Liushusaurus [10]. Comparison of ingested remains preserved across Paraves suggests that dromaeosaurids retained the plesiomorphic condition in which ingested prey were fully digested, rather than egested, as has been demonstrated was the case in the probable troodontid Anchiornis [11]. This supports a closer relationship between Aves and Anchiornis [12, 13] and suggests that flight did not precipitate the evolution of pellet egestion in Paraves and that the evolution of the "modern avian" digestive system in paravians was highly homoplastic [14]. A preliminary Jehol food web is reconstructed from current data.}, } @article {pmid31303484, year = {2019}, author = {Xing, L and O'Connor, JK and Chiappe, LM and McKellar, RC and Carroll, N and Hu, H and Bai, M and Lei, F}, title = {A New Enantiornithine Bird with Unusual Pedal Proportions Found in Amber.}, journal = {Current biology : CB}, volume = {29}, number = {14}, pages = {2396-2401.e2}, doi = {10.1016/j.cub.2019.05.077}, pmid = {31303484}, issn = {1879-0445}, mesh = {*Amber ; Animals ; Biological Evolution ; Birds/anatomy & histology/*classification ; Feathers/anatomy & histology ; Foot/*anatomy & histology ; Fossils/*anatomy & histology ; Myanmar ; Phylogeny ; Wings, Animal/anatomy & histology ; }, abstract = {Recent discoveries of vertebrate remains trapped in middle Cretaceous amber from northern Myanmar [1, 2] have provided insights into the morphology of soft-tissue structures in extinct animals [3-7], in particular, into the evolution and paleobiology of early birds [4, 8, 9]. So far, five bird specimens have been described from Burmese amber: two isolated wings, an isolated foot with wing fragment, and two partial skeletons [4, 8-10]. Most of these specimens contain the remains of juvenile enantiornithine birds [4]. Here, we describe a new specimen of enantiornithine bird in amber, collected at the Angbamo locality in the Hukawng Valley. The new specimen includes a partial right hindlimb and remiges from an adult or subadult bird. Its foot, of which the third digit is much longer than the second and fourth digits, is distinct from those of all other currently recognized Mesozoic and extant birds. Based on the autapomorphic foot morphology, we erect a new taxon, Elektorornis chenguangi gen. et sp. nov. We suggest that the elongated third digit was employed in a unique foraging strategy, highlighting the bizarre morphospace in which early birds operated.}, } @article {pmid31217602, year = {2019}, author = {Shawkey, MD and D'Alba, L}, title = {Egg pigmentation probably has an early Archosaurian origin.}, journal = {Nature}, volume = {570}, number = {7761}, pages = {E43-E45}, pmid = {31217602}, issn = {1476-4687}, mesh = {Animals ; Biological Evolution ; Color ; *Dinosaurs ; Pigmentation ; }, } @article {pmid31164250, year = {2019}, author = {Benton, MJ and Dhouailly, D and Jiang, B and McNamara, M}, title = {The Early Origin of Feathers.}, journal = {Trends in ecology & evolution}, volume = {34}, number = {9}, pages = {856-869}, doi = {10.1016/j.tree.2019.04.018}, pmid = {31164250}, issn = {1872-8383}, mesh = {Animals ; Biological Evolution ; *Dinosaurs ; Ecosystem ; *Feathers ; Fossils ; }, abstract = {Feathers have long been regarded as the innovation that drove the success of birds. However, feathers have been reported from close dinosaurian relatives of birds, and now from ornithischian dinosaurs and pterosaurs, the cousins of dinosaurs. Incomplete preservation makes these reports controversial. If true, these findings shift the origin of feathers back 80 million years before the origin of birds. Gene regulatory networks show the deep homology of scales, feathers, and hairs. Hair and feathers likely evolved in the Early Triassic ancestors of mammals and birds, at a time when synapsids and archosaurs show independent evidence of higher metabolic rates (erect gait and endothermy), as part of a major resetting of terrestrial ecosystems following the devastating end-Permian mass extinction.}, } @article {pmid31068719, year = {2019}, author = {Wang, M and O'Connor, JK and Xu, X and Zhou, Z}, title = {A new Jurassic scansoriopterygid and the loss of membranous wings in theropod dinosaurs.}, journal = {Nature}, volume = {569}, number = {7755}, pages = {256-259}, pmid = {31068719}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; China ; Dinosaurs/*anatomy & histology/*classification ; Flight, Animal ; *Fossils ; Phylogeny ; *Wings, Animal/anatomy & histology ; }, abstract = {Powered flight evolved independently in vertebrates in the pterosaurs, birds and bats, each of which has a different configuration of the bony elements and epidermal structures that form the wings[1,2]. Whereas the early fossil records of pterosaurs and bats are sparse, mounting evidence (primarily from China) of feathered non-avian dinosaurs and stemward avians that derive primarily from the Middle-Upper Jurassic and Lower Cretaceous periods has enabled the slow piecing together of the origins of avian flight[3,4]. These fossils demonstrate that, close to the origin of flight, dinosaurs closely related to birds were experimenting with a diversity of wing structures[3,5]. One of the most surprising of these is that of the scansoriopterygid (Theropoda, Maniraptora) Yi qi, which has membranous wings-a flight apparatus that was previously unknown among theropods but that is used by both the pterosaur and bat lineages[6]. This observation was not universally accepted[7]. Here we describe a newly identified scansoriopterygid-which we name Ambopteryx longibrachium, gen. et sp. nov.-from the Upper Jurassic period. This specimen provides support for the widespread existence of membranous wings and the styliform element in the Scansoriopterygidae, as well as evidence for the diet of this enigmatic theropod clade. Our analyses show that marked changes in wing architecture evolved near the split between the Scansoriopterygidae and the avian lineage, as the two clades travelled along very different paths to becoming volant. The membranous wings supported by elongate forelimbs that are present in scansoriopterygids probably represent a short-lived experimentation with volant behaviour, and feathered wings were ultimately favoured during the later evolution of Paraves.}, } @article {pmid31048911, year = {2019}, author = {Talori, YS and Zhao, JS and Liu, YF and Lu, WX and Li, ZH and O'Connor, JK}, title = {Identification of avian flapping motion from non-volant winged dinosaurs based on modal effective mass analysis.}, journal = {PLoS computational biology}, volume = {15}, number = {5}, pages = {e1006846}, pmid = {31048911}, issn = {1553-7358}, mesh = {Animals ; Biological Evolution ; Biomechanical Phenomena ; Birds/physiology ; Dinosaurs/anatomy & histology/*physiology ; Feathers ; Flight, Animal/*physiology ; Forelimb/physiology ; Fossils ; Hindlimb/physiology ; Locomotion ; Motion ; Phylogeny ; Wings, Animal/anatomy & histology/*physiology ; }, abstract = {The origin of avian flight is one of the most controversial debates in Paleontology. This paper investigates the wing performance of Caudipteryx, the most basal non-volant dinosaur with pennaceous feathered forelimbs by using modal effective mass theory. From a mechanical standpoint, the forced vibrations excited by hindlimb locomotion stimulate the movement of wings, creating a flapping-like motion in response. This shows that the origin of the avian flight stroke should lie in a completely natural process of active locomotion on the ground. In this regard, flapping in the history of evolution of avian flight should have already occurred when the dinosaurs were equipped with pennaceous remiges and rectrices. The forced vibrations provided the initial training for flapping the feathered wings of theropods similar to Caudipteryx.}, } @article {pmid31024012, year = {2019}, author = {Qiu, R and Wang, X and Wang, Q and Li, N and Zhang, J and Ma, Y}, title = {A new caudipterid from the Lower Cretaceous of China with information on the evolution of the manus of Oviraptorosauria.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {6431}, pmid = {31024012}, issn = {2045-2322}, mesh = {Animals ; *Biological Evolution ; Bone and Bones/anatomy & histology ; China ; Dinosaurs/*anatomy & histology/classification ; Extremities/*anatomy & histology ; Paleontology ; }, abstract = {Caudipteridae is a basal clade of Oviraptorosauria, all known species from the Early Cretaceous Jehol Biota of northeastern China. They were one of the first feathered dinosaur groups discovered, and possessed avian-like pennaceous remiges and rectrices. Their discovery provided significant information on early oviraptorosaurian evolution and the origins of birds and feathers. Here we describe a new caudipterid species Xingtianosaurus ganqi gen. et sp. nov. from the Lower Cretaceous Yixian Formation of Liaoning Province, China. This new taxon differs from other caudipterids by a small pleurocoel close to the dorsal edge of the lateral surface of the dorsal vertebrate centrum, a humerus longer than the scapula, a proportionally long ulna, a relatively small radiale angle, and a relatively short metacarpal I. The phylogenetic results shows X. ganqi is an early diverging caudipterid. It exhibits a mosaic morphology, providing new morphological information on early manual evolution of Oviraptorosauria, and giving new light on the evolution of radiale angle among Coelurosauria.}, } @article {pmid31015542, year = {2019}, author = {McCoy, VE and Gabbott, SE and Penkman, K and Collins, MJ and Presslee, S and Holt, J and Grossman, H and Wang, B and Solórzano Kraemer, MM and Delclòs, X and Peñalver, E}, title = {Ancient amino acids from fossil feathers in amber.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {6420}, pmid = {31015542}, issn = {2045-2322}, mesh = {Amber/*chemistry ; Amino Acids/chemistry/history/*isolation & purification ; Animals ; Birds/anatomy & histology ; Chromatography, Reverse-Phase ; Dinosaurs/anatomy & histology ; Egg Shell/*chemistry ; Extinction, Biological ; Feathers/anatomy & histology/*chemistry ; Fossils/anatomy & histology/*history ; History, Ancient ; Preservation, Biological ; Proteins/chemistry/history/*isolation & purification ; Proteolysis ; }, abstract = {Ancient protein analysis is a rapidly developing field of research. Proteins ranging in age from the Quaternary to Jurassic are being used to answer questions about phylogeny, evolution, and extinction. However, these analyses are sometimes contentious, and focus primarily on large vertebrates in sedimentary fossilisation environments; there are few studies of protein preservation in fossils in amber. Here we show exceptionally slow racemisation rates during thermal degradation experiments of resin enclosed feathers, relative to previous thermal degradation experiments of ostrich eggshell, coral skeleton, and limpet shell. We also recover amino acids from two specimens of fossil feathers in amber. The amino acid compositions are broadly similar to those of degraded feathers, but concentrations are very low, suggesting that much of the original protein has been degraded and lost. High levels of racemisation in more apolar, slowly racemising amino acids suggest that some of the amino acids were ancient and therefore original. Our findings indicate that the unique fossilisation environment inside amber shows potential for the recovery of ancient amino acids and proteins.}, } @article {pmid30963907, year = {2018}, author = {Eliason, CM and Clarke, JA}, title = {Metabolic physiology explains macroevolutionary trends in the melanic colour system across amniotes.}, journal = {Proceedings. Biological sciences}, volume = {285}, number = {1893}, pages = {20182014}, pmid = {30963907}, issn = {1471-2954}, mesh = {Animals ; *Biological Evolution ; Birds/*physiology ; Color ; Energy Metabolism/*physiology ; Mammals/*physiology ; Melanosomes/*physiology ; Pigments, Biological/physiology ; Reptiles/*physiology ; }, abstract = {Metabolism links organisms to their environment through its effects on thermoregulation, feeding behaviour and energetics. Genes involved in metabolic processes have known pleiotropic effects on some melanic colour traits. Understanding links between physiology and melanic colour is critical for understanding the role of, and potential constraints on, colour production. Despite considerable variation in metabolic rates and presumed ancestral melanic coloration in vertebrates, few studies have looked at a potential relationship between these two systems in a comparative framework. Here, we test the hypothesis that changes in melanosome shape in integumentary structures track metabolic rate variation across amniotes. Using multivariate comparative analyses and incorporating both extant and fossil taxa, we find significantly faster rates of melanosome shape evolution in taxa with high metabolic rates, as well as both colour- and clade-specific differences in the relationship between metabolic rate and melanosome shape. Phylogenetic tests recover an expansion in melanosome morphospace in maniraptoran dinosaurs, as well as rate shifts within birds (in songbirds) and mammals. These findings indicate another core phenotype influenced by metabolic changes in vertebrates. They also provide a framework for testing clade-specific gene expression patterns in the melanocortin system and may improve colour reconstructions in extinct taxa.}, } @article {pmid30922926, year = {2020}, author = {Griffin, DK and Larkin, DM and O'Connor, RE}, title = {Time lapse: A glimpse into prehistoric genomics.}, journal = {European journal of medical genetics}, volume = {63}, number = {2}, pages = {103640}, pmid = {30922926}, issn = {1878-0849}, support = {BB/E010652/1/BB_/Biotechnology and Biological Sciences Research Council/United Kingdom ; }, mesh = {Animals ; Birds/genetics ; Chromosome Aberrations ; Chromosomes ; Dinosaurs/genetics ; Evolution, Molecular ; Gene Ontology ; *Genome ; *Genomics/history ; History, Ancient ; Humans ; Karyotype ; Phenotype ; }, abstract = {For the purpose of this review, 'time-lapse' refers to the reconstruction of ancestral (in this case dinosaur) karyotypes using genome assemblies of extant species. Such reconstructions are only usually possible when genomes are assembled to 'chromosome level' i.e. a complete representation of all the sequences, correctly ordered contiguously on each of the chromosomes. Recent paleontological evidence is very clear that birds are living dinosaurs, the latest example of dinosaurs emerging from a catastrophic extinction event. Non-avian dinosaurs (ever present in the public imagination through art, and broadcast media) emerged some 240 million years ago and have displayed incredible phenotypic diversity. Here we report on our recent studies to infer the overall karyotype of the Theropod dinosaur lineage from extant avian chromosome level genome assemblies. Our work first focused on determining the likely karyotype of the avian ancestor (most likely a chicken-sized, two-legged, feathered, land dinosaur from the Jurassic period) finding karyotypic similarity to the chicken. We then took the work further to determine the likely karyotype of the bird-lizard ancestor and the chromosomal changes (chiefly translocations and inversions) that occurred between then and modern birds. A combination of bioinformatics and cross-species fluorescence in situ hybridization (zoo-FISH) uncovered a considerable number of translocations and fissions from a 'lizard-like' genome structure of 2n = 36-46 to one similar to that of soft-shelled turtles (2n = 66) from 275 to 255 million years ago (mya). Remarkable karyotypic similarities between some soft-shelled turtles and chicken suggests that there were few translocations from the bird-turtle ancestor (plus ∼7 fissions) through the dawn of the dinosaurs and pterosaurs, through the theropod linage and on to most to modern birds. In other words, an avian-like karyotype was in place about 240mya when the dinosaurs and pterosaurs first emerged. We mapped 49 chromosome inversions from then to the present day, uncovering some gene ontology enrichment in evolutionary breakpoint regions. This avian-like karyotype with its many (micro)chromosomes provides the basis for variation (the driver of natural selection) through increased random segregation and recombination. It may therefore contribute to the ability of dinosaurs to survive multiple extinction events, emerging each time as speciose and diverse.}, } @article {pmid30760849, year = {2019}, author = {Eastick, DL and Tattersall, GJ and Watson, SJ and Lesku, JA and Robert, KA}, title = {Cassowary casques act as thermal windows.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {1966}, pmid = {30760849}, issn = {2045-2322}, mesh = {Animals ; Birds ; Body Temperature/*physiology ; Dromaiidae/*physiology ; Thermogenesis/*physiology ; Thermography/*veterinary ; Weather ; }, abstract = {Many ideas have been put forward for the adaptive value of the cassowary casque; and yet, its purpose remains speculative. Homeothermic animals elevate body temperature through metabolic heat production. Heat gain must be offset by heat loss to maintain internal temperatures within a range for optimal performance. Living in a tropical climate, cassowaries, being large bodied, dark feathered birds, are under thermal pressure to offload heat. We tested the original hypothesis that the casque acts as a thermal window. With infrared thermographic analyses of living cassowaries over an expansive range of ambient temperatures, we provide evidence that the casque acts as a thermal radiator, offloading heat at high temperatures and restricting heat loss at low temperatures. Interestingly, at intermediate temperatures, the casque appears thermally heterogeneous, with the posterior of the casque heating up before the front half. These findings might have implications for the function of similar structures in avian and non-avian dinosaurs.}, } @article {pmid30759416, year = {2019}, author = {Campos, APC and de Carvalho, RT and Straker, LC and Salgado, LT and Kellner, A and Farina, M}, title = {Combined microscopy and spectroscopy techniques to characterize a fossilized feather with minimal damage to the specimen.}, journal = {Micron (Oxford, England : 1993)}, volume = {120}, number = {}, pages = {17-24}, doi = {10.1016/j.micron.2019.01.016}, pmid = {30759416}, issn = {1878-4291}, mesh = {Animals ; Feathers/*ultrastructure ; Fossils/*ultrastructure ; Keratins/analysis ; Melanins/analysis ; Melanocytes/cytology ; Melanosomes/*chemistry ; Microscopy, Electron, Scanning ; Microscopy, Electron, Transmission ; Spectrometry, X-Ray Emission ; Spectroscopy, Fourier Transform Infrared ; Sulfur/*analysis ; }, abstract = {The study of fossil feathers has been revitalized in the last few decades and has contributed significantly to paleontological studies of dinosaurs and birds. Specific morphological and physicochemical characteristics of the microscale structures of feathers and the protein keratin are key targets when preserved during the fossilization process. Keratin is a fibrous protein that composes some hard tissues such as hair, nails and feathers. It is part of the so called intermediate filaments inside keratinocyte cells and is rich in sulfur containing amino acid cysteine. To date, different microscopy and analytical methods have been used for the analysis and detailed characterization and classification of feathers. However, in this work we showed that analytical optical and electron microscopies can be quick and precise methods with minimal effects on the sample during analysis. This association of different approaches on the same sample results in correlative data albeit in different length scales. Intracellular bodies called melanosomes originally present in melanocyte cells were identified with Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), and had well-defined orientation and a mean aspect ratio comparable to melanosomes extant in dark feathers. The detection of sulphur in melanosomes via Energy Dispersive Spectroscopy both in SEM and TEM shows that, along the fossilization process, sulphur from the degraded keratin matrix could have been trapped inside the melanosomes. Chemical groups that make up keratin and melanin in the fossil sample were detected via FT-IR Spectroscopy and Confocal Laser Scanning Microscopy (CLSM). The use of combined analytical microscopy techniques can contribute significantly to the study of fossils generating precise results with minimum damage to the original sample.}, } @article {pmid30753719, year = {2019}, author = {Havstad, JC and Smith, NA}, title = {Fossils with Feathers and Philosophy of Science.}, journal = {Systematic biology}, volume = {68}, number = {5}, pages = {840-851}, pmid = {30753719}, issn = {1076-836X}, mesh = {Animals ; *Biological Evolution ; Birds/classification ; Classification/*methods ; Dinosaurs/classification ; *Feathers ; *Fossils ; Models, Theoretical ; Science/trends ; }, abstract = {The last half century of paleornithological research has transformed the way that biologists perceive the evolutionary history of birds. This transformation has been driven, since 1969, by a series of exciting fossil discoveries combined with intense scientific debate over how best to interpret these discoveries. Ideally, as evidence accrues and results accumulate, interpretive scientific agreement forms. But this has not entirely happened in the debate over avian origins: the accumulation of scientific evidence and analyses has had some effect, but not a conclusive one, in terms of resolving the question of avian origins. Although the majority of biologists have come to accept that birds are dinosaurs, there is lingering and, in some quarters, strident opposition to this view. In order to both understand the ongoing disagreement about avian origins and generate a prediction about the future of the debate, here we use a revised model of scientific practice to assess the current and historical state of play surrounding the topic of bird evolutionary origins. Many scientists are familiar with the metascientific scholars Sir Karl Popper and Thomas Kuhn, and these are the primary figures that have been appealed to so far, in prior attempts to assess the dispute. But we demonstrate that a variation of Imre Lakatos's model of progressive versus degenerative research programmes provides a novel and productive assessment of the debate. We establish that a refurbished Lakatosian account both explains the intractability of the dispute and predicts a likely outcome for the debate about avian origins. In short, here, we offer a metascientific tool for rationally assessing competing theories-one that allows researchers involved in seemingly intractable scientific disputes to advance their debates.}, } @article {pmid30723614, year = {2019}, author = {Cincotta, A and Pestchevitskaya, EB and Sinitsa, SM and Markevich, VS and Debaille, V and Reshetova, SA and Mashchuk, IM and Frolov, AO and Gerdes, A and Yans, J and Godefroit, P}, title = {The rise of feathered dinosaurs: Kulindadromeus zabaikalicus, the oldest dinosaur with 'feather-like' structures.}, journal = {PeerJ}, volume = {7}, number = {}, pages = {e6239}, pmid = {30723614}, issn = {2167-8359}, abstract = {Diverse epidermal appendages including grouped filaments closely resembling primitive feathers in non-avian theropods, are associated with skeletal elements in the primitive ornithischian dinosaur Kulindadromeus zabaikalicus from the Kulinda locality in south-eastern Siberia. This discovery suggests that "feather-like" structures did not evolve exclusively in theropod dinosaurs, but were instead potentially widespread in the whole dinosaur clade. The dating of the Kulinda locality is therefore particularly important for reconstructing the evolution of "feather-like" structures in dinosaurs within a chronostratigraphic framework. Here we present the first dating of the Kulinda locality, combining U-Pb analyses (LA-ICP-MS) on detrital zircons and monazites from sedimentary rocks of volcaniclastic origin and palynological observations. Concordia ages constrain the maximum age of the volcaniclastic deposits at 172.8 ± 1.6 Ma, corresponding to the Aalenian (Middle Jurassic). The palynological assemblage includes taxa that are correlated to Bathonian palynozones from western Siberia, and therefore constrains the minimum age of the deposits. The new U-Pb ages, together with the palynological data, provide evidence of a Bathonian age-between 168.3 ± 1.3 Ma and 166.1 ± 1.2 Ma-for Kulindadromeus. This is older than the previous Late Jurassic to Early Cretaceous ages tentatively based on local stratigraphic correlations. A Bathonian age is highly consistent with the phylogenetic position of Kulindadromeus at the base of the neornithischian clade and suggests that cerapodan dinosaurs originated in Asia during the Middle Jurassic, from a common ancestor that closely looked like Kulindadromeus. Our results consequently show that Kulindadromeus is the oldest known dinosaur with "feather-like" structures discovered so far.}, } @article {pmid30718905, year = {2019}, author = {Kaye, TG and Pittman, M and Mayr, G and Schwarz, D and Xu, X}, title = {Detection of lost calamus challenges identity of isolated Archaeopteryx feather.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {1182}, pmid = {30718905}, issn = {2045-2322}, mesh = {Animals ; Dinosaurs/*classification ; Feathers/*anatomy & histology/diagnostic imaging ; Fossils/*anatomy & histology ; Optical Imaging ; }, abstract = {In 1862, a fossil feather from the Solnhofen quarries was described as the holotype of the iconic Archaeopteryx lithographica. The isolated feather's identification has been problematic, and the fossil was considered either a primary, secondary or, most recently, a primary covert. The specimen is surrounded by the 'mystery of the missing quill'. The calamus described in the original paper is unseen today, even under x-ray fluorescence and UV imaging, challenging its original existence. We answer this question using Laser-Stimulated Fluorescence (LSF) through the recovery of the geochemical halo from the original calamus matching the published description. Our study therefore shows that new techniques applied to well-studied iconic fossils can still provide valuable insights. The morphology of the complete feather excludes it as a primary, secondary or tail feather of Archaeopteryx. However, it could be a covert or a contour feather, especially since the latter are not well known in Archaeopteryx. The possibility remains that it stems from a different feathered dinosaur that lived in the Solnhofen Archipelago. The most recent analysis of the isolated feather considers it to be a primary covert. If this is the case, it lacks a distinct s-shaped centerline found in modern primary coverts that appears to be documented here for the first time.}, } @article {pmid30700773, year = {2019}, author = {Xing, L and McKellar, RC and O'Connor, JK and Bai, M and Tseng, K and Chiappe, LM}, title = {A fully feathered enantiornithine foot and wing fragment preserved in mid-Cretaceous Burmese amber.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {927}, pmid = {30700773}, issn = {2045-2322}, mesh = {*Amber ; Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology ; *Feathers ; *Fossils ; Wings, Animal/*anatomy & histology ; }, abstract = {Over the last three years, Burmese amber (~99 Ma, from Myanmar) has provided a series of immature enantiornithine skeletal remains preserved in varying developmental stages and degrees of completeness. These specimens have improved our knowledge based on compression fossils in Cretaceous sedimentary rocks, adding details of three-dimensional structure and soft tissues that are rarely preserved elsewhere. Here we describe a remarkably well-preserved foot, accompanied by part of the wing plumage. These body parts were likely dismembered, entering the resin due to predatory or scavenging behaviour by a larger animal. The new specimen preserves contour feathers on the pedal phalanges together with enigmatic scutellae scale filament (SSF) feathers on the foot, providing direct analogies to the plumage patterns observed in modern birds, and those cultivated through developmental manipulation studies. Ultimately, this connection may allow researchers to observe how filamentous dinosaur 'protofeathers' developed-testing theories using evolutionary holdovers in modern birds.}, } @article {pmid30692253, year = {2019}, author = {Pan, Y and Zheng, W and Sawyer, RH and Pennington, MW and Zheng, X and Wang, X and Wang, M and Hu, L and O'Connor, J and Zhao, T and Li, Z and Schroeter, ER and Wu, F and Xu, X and Zhou, Z and Schweitzer, MH}, title = {The molecular evolution of feathers with direct evidence from fossils.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {116}, number = {8}, pages = {3018-3023}, pmid = {30692253}, issn = {1091-6490}, mesh = {Animals ; Birds ; Dinosaurs ; *Evolution, Molecular ; Feathers/*chemistry/ultrastructure ; Fossils ; Keratins/*chemistry ; Skin/chemistry/ultrastructure ; beta-Keratins/*chemistry ; }, abstract = {Dinosaur fossils possessing integumentary appendages of various morphologies, interpreted as feathers, have greatly enhanced our understanding of the evolutionary link between birds and dinosaurs, as well as the origins of feathers and avian flight. In extant birds, the unique expression and amino acid composition of proteins in mature feathers have been shown to determine their biomechanical properties, such as hardness, resilience, and plasticity. Here, we provide molecular and ultrastructural evidence that the pennaceous feathers of the Jurassic nonavian dinosaur Anchiornis were composed of both feather β-keratins and α-keratins. This is significant, because mature feathers in extant birds are dominated by β-keratins, particularly in the barbs and barbules forming the vane. We confirm here that feathers were modified at both molecular and morphological levels to obtain the biomechanical properties for flight during the dinosaur-bird transition, and we show that the patterns and timing of adaptive change at the molecular level can be directly addressed in exceptionally preserved fossils in deep time.}, } @article {pmid30568284, year = {2019}, author = {D'Alba, L}, title = {Pterosaur plumage.}, journal = {Nature ecology & evolution}, volume = {3}, number = {1}, pages = {12-13}, pmid = {30568284}, issn = {2397-334X}, mesh = {Animals ; Dinosaurs/*anatomy & histology ; *Feathers ; Fossils ; }, } @article {pmid30568282, year = {2019}, author = {Yang, Z and Jiang, B and McNamara, ME and Kearns, SL and Pittman, M and Kaye, TG and Orr, PJ and Xu, X and Benton, MJ}, title = {Pterosaur integumentary structures with complex feather-like branching.}, journal = {Nature ecology & evolution}, volume = {3}, number = {1}, pages = {24-30}, pmid = {30568282}, issn = {2397-334X}, mesh = {Animals ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; Fossils ; Integumentary System/*anatomy & histology ; Melanosomes ; }, abstract = {Pterosaurs were the first vertebrates to achieve true flapping flight, but in the absence of living representatives, many questions concerning their biology and lifestyle remain unresolved. Pycnofibres-the integumentary coverings of pterosaurs-are particularly enigmatic: although many reconstructions depict fur-like coverings composed of pycnofibres, their affinities and function are not fully understood. Here, we report the preservation in two anurognathid pterosaur specimens of morphologically diverse pycnofibres that show diagnostic features of feathers, including non-vaned grouped filaments and bilaterally branched filaments, hitherto considered unique to maniraptoran dinosaurs, and preserved melanosomes with diverse geometries. These findings could imply that feathers had deep evolutionary origins in ancestral archosaurs, or that these structures arose independently in pterosaurs. The presence of feather-like structures suggests that anurognathids, and potentially other pterosaurs, possessed a dense filamentous covering that probably functioned in thermoregulation, tactile sensing, signalling and aerodynamics.}, } @article {pmid30552395, year = {2018}, author = {Talori, YS and Liu, YF and Zhao, JS and Sullivan, C and O'Connor, JK and Li, ZH}, title = {Winged forelimbs of the small theropod dinosaur Caudipteryx could have generated small aerodynamic forces during rapid terrestrial locomotion.}, journal = {Scientific reports}, volume = {8}, number = {1}, pages = {17854}, pmid = {30552395}, issn = {2045-2322}, support = {51575291//National Natural Science Foundation of China (National Science Foundation of China)/International ; }, mesh = {Animals ; Computer Simulation ; Dinosaurs/*anatomy & histology/*physiology ; Forelimb/*anatomy & histology/*physiology ; *Locomotion ; Models, Theoretical ; Robotics ; Wings, Animal/*anatomy & histology/*physiology ; }, abstract = {Pennaceous feathers capable of forming aerodynamic surfaces are characteristic of Pennaraptora, the group comprising birds and their closest relatives among non-avian dinosaurs. However, members of the basal pennaraptoran lineage Oviraptorosauria were clearly flightless, and the function of pennaceous feathers on the forelimb in oviraptorosaurs is still uncertain. In the basal oviraptorosaur Caudipteryx both the skeleton and the plumage, which includes pennaceous feathers forming wing-like arrangements on the forelimbs, are well known. We used mathematical analyses, computer simulations and experiments on a robot Caudipteryx with realistic wing proportions to test whether the wings of Caudipteryx could have generated aerodynamic forces useful in rapid terrestrial locomotion. These various approaches show that, if both wings were held in a fixed and laterally extended position, they would have produced only small amounts of lift and drag. A partial simulation of flapping while running showed similarly limited aerodynamic force production. These results are consistent with the possibility that pennaceous feathers first evolved for a non-locomotor function such as display, but the effects of flapping and the possible contribution of the wings during manoeuvres such as braking and turning remain to be more fully investigated.}, } @article {pmid30524148, year = {2018}, author = {Saitta, ET and Clapham, C and Vinther, J}, title = {Experimental subaqueous burial of a bird carcass and compaction of plumage.}, journal = {Palaontologische zeitschrift}, volume = {92}, number = {4}, pages = {727-732}, pmid = {30524148}, issn = {0031-0220}, abstract = {'Exceptional fossils' of dinosaurs preserving feathers have radically changed the way we view their paleobiology and the evolution of birds. Understanding how such soft tissues preserve is imperative to accurately interpreting the morphology of fossil feathers. Experimental taphonomy has been integral to such investigations. One such experiment used a printing press to mimic compaction, done subaerially and without sediment burial, and concluded that the leaking of bodily fluid could lead to the clumping of feathers by causing barbs to stick together such that they superficially resemble simpler, less derived, filamentous structures. Here we use a novel, custom-built experimental setup to more accurately mimic subaqueous burial and compaction under low-energy, fine-grain depositional environments applicable to the taphonomic settings most plumage-preserving 'exceptional fossils' are found in. We find that when submerged and subsequently buried and compacted, feathers do not clump together and they maintain their original arrangement. Submersion in fluid in and of itself does not lead to clumping of barbs; this would only occur upon pulling feathers out from water into air. Furthermore, sediment encases the feathers, fixing them in place during compaction. Thus, feather clumping that leads to erroneously plesiomorphic morphological interpretations may not be a taphonomic factor of concern when examining fossil feathers. Our current methodology is amenable to further improvements that will continue to more accurately mimic subaqueous burial and compaction, allowing for various hypothesis testing.}, } @article {pmid30518862, year = {2018}, author = {Lindgren, J and Sjövall, P and Thiel, V and Zheng, W and Ito, S and Wakamatsu, K and Hauff, R and Kear, BP and Engdahl, A and Alwmark, C and Eriksson, ME and Jarenmark, M and Sachs, S and Ahlberg, PE and Marone, F and Kuriyama, T and Gustafsson, O and Malmberg, P and Thomen, A and Rodríguez-Meizoso, I and Uvdal, P and Ojika, M and Schweitzer, MH}, title = {Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur.}, journal = {Nature}, volume = {564}, number = {7736}, pages = {359-365}, doi = {10.1038/s41586-018-0775-x}, pmid = {30518862}, issn = {1476-4687}, support = {ECCS-1542015//National Science Foundation/International ; }, mesh = {Adaptation, Physiological ; Adipose Tissue/anatomy & histology/chemistry ; Animals ; *Biological Evolution ; *Body Temperature Regulation ; Dermis/anatomy & histology/chemistry ; Dinosaurs/*anatomy & histology/*physiology ; Dolphins ; Epidermis/anatomy & histology/chemistry ; Female ; *Fossils ; *Homeostasis ; Keratinocytes/chemistry ; Lipids/analysis ; Male ; Melanins/analysis ; Melanophores/chemistry ; Porpoises ; Proteins/analysis ; }, abstract = {Ichthyosaurs are extinct marine reptiles that display a notable external similarity to modern toothed whales. Here we show that this resemblance is more than skin deep. We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius. Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers. These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy. Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment. Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation. Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.}, } @article {pmid30464264, year = {2018}, author = {Wiemann, J and Yang, TR and Norell, MA}, title = {Dinosaur egg colour had a single evolutionary origin.}, journal = {Nature}, volume = {563}, number = {7732}, pages = {555-558}, doi = {10.1038/s41586-018-0646-5}, pmid = {30464264}, issn = {1476-4687}, mesh = {Animals ; Biliverdine/metabolism ; *Biological Evolution ; Color ; *Dinosaurs/classification ; Egg Shell/*anatomy & histology ; Fossils ; Phylogeny ; Pigmentation/*physiology ; Principal Component Analysis ; Protoporphyrins/metabolism ; }, abstract = {Birds are the only living amniotes with coloured eggs[1-4], which have long been considered to be an avian innovation[1,3]. A recent study has demonstrated the presence of both red-brown protoporphyrin IX and blue-green biliverdin[5]-the pigments responsible for all the variation in avian egg colour-in fossilized eggshell of a nonavian dinosaur[6]. This raises the fundamental question of whether modern birds inherited egg colour from their nonavian dinosaur ancestors, or whether egg colour evolved independently multiple times. Here we present a phylogenetic assessment of egg colour in nonavian dinosaurs. We applied high-resolution Raman microspectroscopy to eggshells that represent all of the major clades of dinosaurs, and found that egg colour pigments were preserved in all eumaniraptorans: egg colour had a single evolutionary origin in nonavian theropod dinosaurs. The absence of colour in ornithischian and sauropod eggs represents a true signal rather than a taphonomic artefact. Pigment surface maps revealed that nonavian eumaniraptoran eggs were spotted and speckled, and colour pattern diversity in these eggs approaches that in extant birds, which indicates that reproductive behaviours in nonavian dinosaurs were far more complex than previously known[3]. Depth profiles demonstrated identical mechanisms of pigment deposition in nonavian and avian dinosaur eggs. Birds were not the first amniotes to produce coloured eggs: as with many other characteristics[7,8] this is an attribute that evolved deep within the dinosaur tree and long before the spectacular radiation of modern birds.}, } @article {pmid30406089, year = {2018}, author = {Heers, AM and Rankin, JW and Hutchinson, JR}, title = {Building a Bird: Musculoskeletal Modeling and Simulation of Wing-Assisted Incline Running During Avian Ontogeny.}, journal = {Frontiers in bioengineering and biotechnology}, volume = {6}, number = {}, pages = {140}, pmid = {30406089}, issn = {2296-4185}, abstract = {Flapping flight is the most power-demanding mode of locomotion, associated with a suite of anatomical specializations in extant adult birds. In contrast, many developing birds use their forelimbs to negotiate environments long before acquiring "flight adaptations," recruiting their developing wings to continuously enhance leg performance and, in some cases, fly. How does anatomical development influence these locomotor behaviors? Isolating morphological contributions to wing performance is extremely challenging using purely empirical approaches. However, musculoskeletal modeling and simulation techniques can incorporate empirical data to explicitly examine the functional consequences of changing morphology by manipulating anatomical parameters individually and estimating their effects on locomotion. To assess how ontogenetic changes in anatomy affect locomotor capacity, we combined existing empirical data on muscle morphology, skeletal kinematics, and aerodynamic force production with advanced biomechanical modeling and simulation techniques to analyze the ontogeny of pectoral limb function in a precocial ground bird (Alectoris chukar). Simulations of wing-assisted incline running (WAIR) using these newly developed musculoskeletal models collectively suggest that immature birds have excess muscle capacity and are limited more by feather morphology, possibly because feathers grow more quickly and have a different style of growth than bones and muscles. These results provide critical information about the ontogeny and evolution of avian locomotion by (i) establishing how muscular and aerodynamic forces interface with the skeletal system to generate movement in morphing juvenile birds, and (ii) providing a benchmark to inform biomechanical modeling and simulation of other locomotor behaviors, both across extant species and among extinct theropod dinosaurs.}, } @article {pmid30002976, year = {2018}, author = {Yang, TR and Chen, YH and Wiemann, J and Spiering, B and Sander, PM}, title = {Fossil eggshell cuticle elucidates dinosaur nesting ecology.}, journal = {PeerJ}, volume = {6}, number = {}, pages = {e5144}, pmid = {30002976}, issn = {2167-8359}, abstract = {The cuticle layer consisting mainly of lipids and hydroxyapatite (HAp) atop the mineralized avian eggshell is a protective structure that prevents the egg from dehydration and microbial invasions. Previous ornithological studies have revealed that the cuticle layer is also involved in modulating the reflectance of eggshells in addition to pigments (protoporphyrin and biliverdin). Thus, the cuticle layer represents a crucial trait that delivers ecological signals. While present in most modern birds, direct evidence for cuticle preservation in stem birds and non-avian dinosaurs is yet missing. Here we present the first direct and chemical evidence for the preservation of the cuticle layer on dinosaur eggshells. We analyze several theropod eggshells from various localities, including oviraptorid Macroolithus yaotunensis eggshells from the Late Cretaceous deposits of Henan, Jiangxi, and Guangdong in China and alvarezsaurid Triprismatoolithus eggshell from the Two Medicine Formation of Montana, United States, with the scanning electron microscope (SEM), electron probe micro-analysis (EPMA), and Raman spectroscopy (RS). The elemental analysis with EPMA shows high concentration of phosphorus at the boundary between the eggshell and sediment, representing the hydroxyapatitic cuticle layer (HAp). Depletion of phosphorus in sediment excludes the allochthonous origin of the phosphorus in these eggshells. The chemometric analysis of Raman spectra collected from fossil and extant eggs provides further supportive evidence for the cuticle preservation in oviraptorid and probable alvarezsaurid eggshells. In accordance with our previous discovery of pigments preserved in Cretaceous oviraptorid dinosaur eggshells, we validate the cuticle preservation on dinosaur eggshells through deep time and offer a yet unexplored resource for chemical studies targeting the evolution of dinosaur nesting ecology. Our study also suggests that the cuticle structure can be traced far back to maniraptoran dinosaurs and enhance their reproductive success in a warm and mesic habitat such as Montana and southern China during the Late Cretaceous.}, } @article {pmid29899503, year = {2018}, author = {Rashid, DJ and Surya, K and Chiappe, LM and Carroll, N and Garrett, KL and Varghese, B and Bailleul, A and O'Connor, JK and Chapman, SC and Horner, JR}, title = {Avian tail ontogeny, pygostyle formation, and interpretation of juvenile Mesozoic specimens.}, journal = {Scientific reports}, volume = {8}, number = {1}, pages = {9014}, pmid = {29899503}, issn = {2045-2322}, support = {P20 GM103474/GM/NIGMS NIH HHS/United States ; P30 GM110732/GM/NIGMS NIH HHS/United States ; R01 DC009236/DC/NIDCD NIH HHS/United States ; }, mesh = {Amber/chemistry ; Animals ; Biological Evolution ; Birds/anatomy & histology/*growth & development ; Chickens/anatomy & histology/growth & development ; Feathers/anatomy & histology/growth & development ; *Fossils ; *Morphogenesis ; Spine/anatomy & histology/growth & development ; Tail/anatomy & histology/*growth & development ; Time Factors ; X-Ray Microtomography ; }, abstract = {The avian tail played a critical role in the evolutionary transition from long- to short-tailed birds, yet its ontogeny in extant birds has largely been ignored. This deficit has hampered efforts to effectively identify intermediate species during the Mesozoic transition to short tails. Here we show that fusion of distal vertebrae into the pygostyle structure does not occur in extant birds until near skeletal maturity, and mineralization of vertebral processes also occurs long after hatching. Evidence for post-hatching pygostyle formation is also demonstrated in two Cretaceous specimens, a juvenile enantiornithine and a subadult basal ornithuromorph. These findings call for reinterpretations of Zhongornis haoae, a Cretaceous bird hypothesized to be an intermediate in the long- to short-tailed bird transition, and of the recently discovered coelurosaur tail embedded in amber. Zhongornis, as a juvenile, may not yet have formed a pygostyle, and the amber-embedded tail specimen is reinterpreted as possibly avian. Analyses of relative pygostyle lengths in extant and Cretaceous birds suggests the number of vertebrae incorporated into the pygostyle has varied considerably, further complicating the interpretation of potential transitional species. In addition, this analysis of avian tail development reveals the generation and loss of intervertebral discs in the pygostyle, vertebral bodies derived from different kinds of cartilage, and alternative modes of caudal vertebral process morphogenesis in birds. These findings demonstrate that avian tail ontogeny is a crucial parameter specifically for the interpretation of Mesozoic specimens, and generally for insights into vertebrae formation.}, } @article {pmid29802246, year = {2018}, author = {McNamara, ME and Zhang, F and Kearns, SL and Orr, PJ and Toulouse, A and Foley, T and Hone, DWE and Rogers, CS and Benton, MJ and Johnson, D and Xu, X and Zhou, Z}, title = {Fossilized skin reveals coevolution with feathers and metabolism in feathered dinosaurs and early birds.}, journal = {Nature communications}, volume = {9}, number = {1}, pages = {2072}, pmid = {29802246}, issn = {2041-1723}, mesh = {Animals ; *Biological Coevolution ; Birds/*physiology ; Dinosaurs/*physiology ; Epidermis/*physiology/ultrastructure ; Feathers/*physiology/ultrastructure ; Fossils ; Microscopy, Electron, Scanning ; Phylogeny ; }, abstract = {Feathers are remarkable evolutionary innovations that are associated with complex adaptations of the skin in modern birds. Fossilised feathers in non-avian dinosaurs and basal birds provide insights into feather evolution, but how associated integumentary adaptations evolved is unclear. Here we report the discovery of fossil skin, preserved with remarkable nanoscale fidelity, in three non-avian maniraptoran dinosaurs and a basal bird from the Cretaceous Jehol biota (China). The skin comprises patches of desquamating epidermal corneocytes that preserve a cytoskeletal array of helically coiled α-keratin tonofibrils. This structure confirms that basal birds and non-avian dinosaurs shed small epidermal flakes as in modern mammals and birds, but structural differences imply that these Cretaceous taxa had lower body heat production than modern birds. Feathered epidermis acquired many, but not all, anatomically modern attributes close to the base of the Maniraptora by the Middle Jurassic.}, } @article {pmid29535376, year = {2018}, author = {Voeten, DFAE and Cubo, J and de Margerie, E and Röper, M and Beyrand, V and Bureš, S and Tafforeau, P and Sanchez, S}, title = {Wing bone geometry reveals active flight in Archaeopteryx.}, journal = {Nature communications}, volume = {9}, number = {1}, pages = {923}, pmid = {29535376}, issn = {2041-1723}, mesh = {Animals ; *Biological Evolution ; *Birds ; Bone and Bones/anatomy & histology/diagnostic imaging ; Dinosaurs/anatomy & histology ; *Flight, Animal ; Fossils/anatomy & histology/*diagnostic imaging ; Wings, Animal/*anatomy & histology ; X-Ray Microtomography ; }, abstract = {Archaeopteryx is an iconic fossil taxon with feathered wings from the Late Jurassic of Germany that occupies a crucial position for understanding the early evolution of avian flight. After over 150 years of study, its mosaic anatomy unifying characters of both non-flying dinosaurs and flying birds has remained challenging to interpret in a locomotory context. Here, we compare new data from three Archaeopteryx specimens obtained through phase-contrast synchrotron microtomography to a representative sample of archosaurs employing a diverse array of locomotory strategies. Our analyses reveal that the architecture of Archaeopteryx's wing bones consistently exhibits a combination of cross-sectional geometric properties uniquely shared with volant birds, particularly those occasionally utilising short-distance flapping. We therefore interpret that Archaeopteryx actively employed wing flapping to take to the air through a more anterodorsally posteroventrally oriented flight stroke than used by modern birds. This unexpected outcome implies that avian powered flight must have originated before the latest Jurassic.}, } @article {pmid36659012, year = {2018}, author = {Xing, L and O'Connor, JK and McKellar, RC and Chiappe, LM and Bai, M and Tseng, K and Zhang, J and Yang, H and Fang, J and Li, G}, title = {A flattened enantiornithine in mid-Cretaceous Burmese amber: morphology and preservation.}, journal = {Science bulletin}, volume = {63}, number = {4}, pages = {235-243}, doi = {10.1016/j.scib.2018.01.019}, pmid = {36659012}, issn = {2095-9281}, abstract = {Cretaceous amber from Myanmar (∼99 Ma Burmese amber) has become a valuable supplement to the traditional skeletal record of small theropod dinosaurs preserved in sedimentary rocks, particularly for coelurosaurs and enantiornithines. The specimens recovered from this deposit preserve skeletal material and soft tissues in unmatched detail. This provides opportunities to study three-dimensional preservation of soft tissues, microstructure, and pigmentation patterns that are seldom available elsewhere in the fossil record. Ultimately, this line of research provides insights into life stages that are difficult to preserve, the ecology and appearance of the groups involved, and the evolutionary-development of structures such as feathers. Here we describe the most recent discovery from Burmese amber, an articulated skeleton of an enantiornithine bird. This individual has been sectioned along the coronal plane, providing a unique view inside multiple body regions. Osteological observations and plumage patterns support placement within the Enantiornithes, and suggest that the animal may have been a juvenile at the time of death. The specimen has a complex taphonomic history that includes exposure at the surface of a resin flow prior to encapsulation, and may include scavenging by some of the insects trapped within the same amber piece. The chemical composition observed along surface exposures and shallowly buried regions of the body indicate that the specimen has not undergone significant exchange with its surroundings. High iron concentrations are present in regions that preserve soft tissues as carbon films, and calcium distribution corresponds to regions where bones breach the surface of the amber.}, } @article {pmid29382823, year = {2018}, author = {Peñalver, E and Arillo, A and Delclòs, X and Peris, D and Grimaldi, DA and Anderson, SR and Nascimbene, PC and Fuente, RP}, title = {Publisher Correction: Ticks parasitised feathered dinosaurs as revealed by Cretaceous amber assemblages.}, journal = {Nature communications}, volume = {9}, number = {1}, pages = {472}, doi = {10.1038/s41467-018-02913-w}, pmid = {29382823}, issn = {2041-1723}, abstract = {The originally published version of this Article was updated shortly after publication to add the word 'Ticks' to the title, following its inadvertent removal during the production process. This has now been corrected in both the PDF and HTML versions of the Article.}, } @article {pmid29372073, year = {2018}, author = {Kondo, M and Sekine, T and Miyakoshi, T and Kitajima, K and Egawa, S and Seki, R and Abe, G and Tamura, K}, title = {Flight feather development: its early specialization during embryogenesis.}, journal = {Zoological letters}, volume = {4}, number = {}, pages = {2}, pmid = {29372073}, issn = {2056-306X}, abstract = {BACKGROUND: Flight feathers, a type of feather that is unique to extant/extinct birds and some non-avian dinosaurs, are the most evolutionally advanced type of feather. In general, feather types are formed in the second or later generation of feathers at the first and following molting, and the first molting begins at around two weeks post hatching in chicken. However, it has been stated in some previous reports that the first molting from the natal down feathers to the flight feathers is much earlier than that for other feather types, suggesting that flight feather formation starts as an embryonic event. The aim of this study was to determine the inception of flight feather morphogenesis and to identify embryological processes specific to flight feathers in contrast to those of down feathers.

RESULTS: We found that the second generation of feather that shows a flight feather-type arrangement has already started developing by chick embryonic day 18, deep in the skin of the flight feather-forming region. This was confirmed by shh gene expression that shows barb pattern, and the expression pattern revealed that the second generation of feather development in the flight feather-forming region seems to start by embryonic day 14. The first stage at which we detected a specific morphology of the feather bud in the flight feather-forming region was embryonic day 11, when internal invagination of the feather bud starts, while the external morphology of the feather bud is radial down-type.

CONCLUSION: The morphogenesis for the flight feather, the most advanced type of feather, has been drastically modified from the beginning of feather morphogenesis, suggesting that early modification of the embryonic morphogenetic process may have played a crucial role in the morphological evolution of this key innovation. Co-optation of molecular cues for axial morphogenesis in limb skeletal development may be able to modify morphogenesis of the feather bud, giving rise to flight feather-specific morphogenesis of traits.}, } @article {pmid29360744, year = {2018}, author = {Negro, JJ and Finlayson, C and Galván, I}, title = {Melanins in Fossil Animals: Is It Possible to Infer Life History Traits from the Coloration of Extinct Species?.}, journal = {International journal of molecular sciences}, volume = {19}, number = {2}, pages = {}, pmid = {29360744}, issn = {1422-0067}, mesh = {Animals ; Biological Evolution ; Dinosaurs ; Extinction, Biological ; *Fossils ; Melanins/*analysis ; Pigmentation ; Quantitative Trait, Heritable ; Skin Pigmentation ; }, abstract = {Paleo-colour scientists have recently made the transition from describing melanin-based colouration in fossil specimens to inferring life-history traits of the species involved. Two such cases correspond to counter-shaded dinosaurs: dark-coloured due to melanins dorsally, and light-coloured ventrally. We believe that colour reconstruction of fossils based on the shape of preserved microstructures-the majority of paleo-colour studies involve melanin granules-is not without risks. In addition, animals with contrasting dorso-ventral colouration may be under different selection pressures beyond the need for camouflage, including, for instance, visual communication or ultraviolet (UV) protection. Melanin production is costly, and animals may invest less in areas of the integument where pigments are less needed. In addition, melanocytes exposed to UV radiation produce more melanin than unexposed melanocytes. Pigment economization may thus explain the colour pattern of some counter-shaded animals, including extinct species. Even in well-studied extant species, their diversity of hues and patterns is far from being understood; inferring colours and their functions in species only known from one or few specimens from the fossil record should be exerted with special prudence.}, } @article {pmid29335537, year = {2018}, author = {Hu, D and Clarke, JA and Eliason, CM and Qiu, R and Li, Q and Shawkey, MD and Zhao, C and D'Alba, L and Jiang, J and Xu, X}, title = {A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution.}, journal = {Nature communications}, volume = {9}, number = {1}, pages = {217}, pmid = {29335537}, issn = {2041-1723}, mesh = {Animals ; Biological Evolution ; Birds/*anatomy & histology ; Bone and Bones/*anatomy & histology ; Color ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; Flight, Animal ; *Fossils ; Melanosomes ; Wings, Animal/anatomy & histology ; }, abstract = {The Jurassic Yanliao theropods have offered rare glimpses of the early paravian evolution and particularly of bird origins, but, with the exception of the bizarre scansoriopterygids, they have shown similar skeletal and integumentary morphologies. Here we report a distinctive new Yanliao theropod species bearing prominent lacrimal crests, bony ornaments previously known from more basal theropods. It shows longer arm and leg feathers than Anchiornis and tail feathers with asymmetrical vanes forming a tail surface area even larger than that in Archaeopteryx. Nanostructures, interpreted as melanosomes, are morphologically similar to organized, platelet-shaped organelles that produce bright iridescent colours in extant birds. The new species indicates the presence of bony ornaments, feather colour and flight-related features consistent with proposed rapid character evolution and significant diversity in signalling and locomotor strategies near bird origins.}, } @article {pmid29321475, year = {2018}, author = {Prondvai, E and Godefroit, P and Adriaens, D and Hu, DY}, title = {Intraskeletal histovariability, allometric growth patterns, and their functional implications in bird-like dinosaurs.}, journal = {Scientific reports}, volume = {8}, number = {1}, pages = {258}, pmid = {29321475}, issn = {2045-2322}, abstract = {With their elongated forelimbs and variable aerial skills, paravian dinosaurs, a clade also comprising modern birds, are in the hotspot of vertebrate evolutionary research. Inferences on the early evolution of flight largely rely on bone and feather morphology, while osteohistological traits are usually studied to explore life-history characteristics. By sampling and comparing multiple homologous fore- and hind limb elements, we integrate for the first time qualitative and quantitative osteohistological approaches to get insight into the intraskeletal growth dynamics and their functional implications in five paravian dinosaur taxa, Anchiornis, Aurornis, Eosinopteryx, Serikornis, and Jeholornis. Our qualitative assessment implies a considerable diversity in allometric/isometric growth patterns among these paravians. Quantitative analyses show that neither taxa nor homologous elements have characteristic histology, and that ontogenetic stage, element size and the newly introduced relative element precocity only partially explain the diaphyseal histovariability. Still, Jeholornis, the only avialan studied here, is histologically distinct from all other specimens in the multivariate visualizations raising the hypothesis that its bone tissue characteristics may be related to its superior aerial capabilities compared to the non-avialan paravians. Our results warrant further research on the osteohistological correlates of flight and developmental strategies in birds and bird-like dinosaurs.}, } @article {pmid31258911, year = {2018}, author = {Wilson, PF and Smith, MP and Hay, J and Warnett, JM and Attridge, A and Williams, MA}, title = {X-ray computed tomography (XCT) and chemical analysis (EDX and XRF) used in conjunction for cultural conservation: the case of the earliest scientifically described dinosaur Megalosaurus bucklandii.}, journal = {Heritage science}, volume = {6}, number = {1}, pages = {58}, pmid = {31258911}, issn = {2050-7445}, abstract = {This paper demonstrates the combined use of X-ray computed tomography (XCT), energy dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) to evaluate the conservational history of the dentary (lower jaw) of Megalosaurus bucklandii Mantell, 1827, the first scientifically described dinosaur. Previous analysis using XCT revealed that the specimen had undergone at least two phases of repair using two different kinds of plaster, although their composition remained undetermined. Additional chemical analysis using EDX and XRF has allowed the determination of the composition of these unidentified plasters, revealing that they are of similar composition, composed dominantly of 'plaster of Paris' mixed with quartz sand and calcite, potentially from the matrix material of the Stonesfield Slate, with the trace presence of chlorine. One of the plasters unusually contains the pigment minium (naturally occurring lead tetroxide; Pb2 [2+]Pb[4+]O4) whilst the other seems to have an additional coating of barium hydroxide (Ba(OH)2), indicating that these likely represent two separate stages of repair. The potential of this combined approach for evaluating problematic museum objects for conservation is further discussed as is its usage in cultural heritage today.}, } @article {pmid29233973, year = {2017}, author = {Peñalver, E and Arillo, A and Delclòs, X and Peris, D and Grimaldi, DA and Anderson, SR and Nascimbene, PC and Pérez-de la Fuente, R}, title = {parasitised feathered dinosaurs as revealed by Cretaceous amber assemblages.}, journal = {Nature communications}, volume = {8}, number = {1}, pages = {1924}, pmid = {29233973}, issn = {2041-1723}, mesh = {Amber ; Animals ; Dinosaurs/anatomy & histology/*parasitology ; Feathers/parasitology ; Female ; *Fossils ; Male ; Sensilla ; *Ticks/anatomy & histology/classification ; }, abstract = {Ticks are currently among the most prevalent blood-feeding ectoparasites, but their feeding habits and hosts in deep time have long remained speculative. Here, we report direct and indirect evidence in 99 million-year-old Cretaceous amber showing that hard ticks and ticks of the extinct new family Deinocrotonidae fed on blood from feathered dinosaurs, non-avialan or avialan excluding crown-group birds. A †Cornupalpatum burmanicum hard tick is entangled in a pennaceous feather. Two deinocrotonids described as †Deinocroton draculi gen. et sp. nov. have specialised setae from dermestid beetle larvae (hastisetae) attached to their bodies, likely indicating cohabitation in a feathered dinosaur nest. A third conspecific specimen is blood-engorged, its anatomical features suggesting that deinocrotonids fed rapidly to engorgement and had multiple gonotrophic cycles. These findings provide insight into early tick evolution and ecology, and shed light on poorly known arthropod-vertebrate interactions and potential disease transmission during the Mesozoic.}, } @article {pmid29177513, year = {2018}, author = {Wu, P and Yan, J and Lai, YC and Ng, CS and Li, A and Jiang, X and Elsey, RM and Widelitz, R and Bajpai, R and Li, WH and Chuong, CM}, title = {Multiple Regulatory Modules Are Required for Scale-to-Feather Conversion.}, journal = {Molecular biology and evolution}, volume = {35}, number = {2}, pages = {417-430}, pmid = {29177513}, issn = {1537-1719}, support = {R01 AR047364/AR/NIAMS NIH HHS/United States ; R01 AR060306/AR/NIAMS NIH HHS/United States ; }, mesh = {Alligators and Crocodiles ; *Animal Scales ; Animals ; *Biological Evolution ; Chick Embryo ; *Feathers ; Gene Expression Profiling ; Genomics ; Morphogenesis/*genetics ; Phenotype ; Transcription Factors ; beta-Keratins/genetics/metabolism ; }, abstract = {The origin of feathers is an important question in Evo-Devo studies, with the eventual evolution of vaned feathers which are aerodynamic, allowing feathered dinosaurs and early birds to fly and venture into new ecological niches. Studying how feathers and scales are developmentally specified provides insight into how a new organ may evolve. We identified feather-associated genes using genomic analyses. The candidate genes were tested by expressing them in chicken and alligator scale forming regions. Ectopic expression of these genes induced intermediate morphotypes between scales and feathers which revealed several major morphogenetic events along this path: Localized growth zone formation, follicle invagination, epithelial branching, feather keratin differentiation, and dermal papilla formation. In addition to molecules known to induce feathers on scales (retinoic acid, β-catenin), we identified novel scale-feather converters (Sox2, Zic1, Grem1, Spry2, Sox18) which induce one or more regulatory modules guiding these morphogenetic events. Some morphotypes resemble filamentous appendages found in feathered dinosaur fossils, whereas others exhibit characteristics of modern avian feathers. We propose these morpho-regulatory modules were used to diversify archosaur scales and to initiate feather evolution. The regulatory combination and hierarchical integration may have led to the formation of extant feather forms. Our study highlights the importance of integrating discoveries between developmental biology and paleontology.}, } @article {pmid29107548, year = {2017}, author = {Smithwick, FM and Nicholls, R and Cuthill, IC and Vinther, J}, title = {Countershading and Stripes in the Theropod Dinosaur Sinosauropteryx Reveal Heterogeneous Habitats in the Early Cretaceous Jehol Biota.}, journal = {Current biology : CB}, volume = {27}, number = {21}, pages = {3337-3343.e2}, doi = {10.1016/j.cub.2017.09.032}, pmid = {29107548}, issn = {1879-0445}, mesh = {Animals ; Biological Evolution ; Biological Mimicry/*physiology ; Dinosaurs/*anatomy & histology ; Ecosystem ; Feathers/anatomy & histology ; Fossils/*anatomy & histology ; Pigmentation/*physiology ; }, abstract = {Countershading is common across a variety of lineages and ecological time [1-4]. A dark dorsum and lighter ventrum helps to mask the three-dimensional shape of the body by reducing self-shadowing and decreasing conspicuousness, thus helping to avoid detection by predators and prey [1, 2, 4, 5]. The optimal countershading pattern is dictated by the lighting environment, which is in turn dependent upon habitat [1, 3, 5, 6]. With the discovery of fossil melanin [7, 8], it is possible to infer original color patterns from fossils, including countershading [3, 9, 10]. Applying these principles, we describe the pattern of countershading in the diminutive theropod dinosaur Sinosauropteryx from the Early Cretaceous Jehol Biota of Liaoning, China. From reconstructions based on exceptional fossils, the color pattern is compared to predicted optimal countershading transitions based on 3D reconstructions of the animal's abdomen, imaged in different lighting environments. Reconstructed patterns match well with those predicted for animals living in open habitats. Jehol is presumed to have been a predominantly closed forested environment [3, 11, 12], but our results indicate a more heterogeneous range of habitats. Sinosauropteryx is also shown to exhibit a "bandit mask," a common pattern in many living vertebrates, particularly birds, that serves multiple functions including camouflage [13-18]. Sinosauropteryx therefore shows multiple color pattern features likely related to the habitat in which it lived. Our results show how reconstructing the color of extinct animals can inform on their ecologies beyond what may be obvious from skeletal remains alone. VIDEO ABSTRACT.}, } @article {pmid29094706, year = {2017}, author = {Pickrell, J}, title = {Camouflage plumage patterns offer clue to dinosaur's habitat.}, journal = {Nature}, volume = {551}, number = {7678}, pages = {17}, doi = {10.1038/nature.2017.22891}, pmid = {29094706}, issn = {1476-4687}, mesh = {Animals ; *Dinosaurs ; *Ecosystem ; Feathers ; Pigmentation ; }, } @article {pmid29020077, year = {2017}, author = {Liu, D and Chiappe, LM and Serrano, F and Habib, M and Zhang, Y and Meng, Q}, title = {Flight aerodynamics in enantiornithines: Information from a new Chinese Early Cretaceous bird.}, journal = {PloS one}, volume = {12}, number = {10}, pages = {e0184637}, pmid = {29020077}, issn = {1932-6203}, mesh = {Animals ; Biomechanical Phenomena ; Birds/anatomy & histology/*physiology ; Body Weight ; Bone and Bones/anatomy & histology ; Extremities/anatomy & histology ; Feathers/anatomy & histology ; Flight, Animal/*physiology ; *Fossils ; Regression Analysis ; Terminology as Topic ; Time Factors ; }, abstract = {We describe an exquisitely preserved new avian fossil (BMNHC-PH-919) from the Lower Cretaceous Yixian Formation of eastern Inner Mongolia, China. Although morphologically similar to Cathayornithidae and other small-sized enantiornithines from China's Jehol Biota, many morphological features indicate that it represents a new species, here named Junornis houi. The new fossil displays most of its plumage including a pair of elongated, rachis-dominated tail feathers similarly present in a variety of other enantiornithines. BMNHC-PH-919 represents the first record of a Jehol enantiornithine from Inner Mongolia, thus extending the known distribution of these birds into the eastern portion of this region. Furthermore, its well-preserved skeleton and wing outline provide insight into the aerodynamic performance of enantiornithines, suggesting that these birds had evolved bounding flight-a flight mode common to passeriforms and other small living birds-as early as 125 million years ago.}, } @article {pmid28875070, year = {2017}, author = {Wiemann, J and Yang, TR and Sander, PN and Schneider, M and Engeser, M and Kath-Schorr, S and Müller, CE and Sander, PM}, title = {Dinosaur origin of egg color: oviraptors laid blue-green eggs.}, journal = {PeerJ}, volume = {5}, number = {}, pages = {e3706}, pmid = {28875070}, issn = {2167-8359}, abstract = {Protoporphyrin (PP) and biliverdin (BV) give rise to the enormous diversity in avian egg coloration. Egg color serves several ecological purposes, including post-mating signaling and camouflage. Egg camouflage represents a major character of open-nesting birds which accomplish protection of their unhatched offspring against visually oriented predators by cryptic egg coloration. Cryptic coloration evolved to match the predominant shades of color found in the nesting environment. Such a selection pressure for the evolution of colored or cryptic eggs should be present in all open nesting birds and relatives. Many birds are open-nesting, but protect their eggs by continuous brooding, and thus exhibit no or minimal eggshell pigmentation. Their closest extant relatives, crocodiles, protect their eggs by burial and have unpigmented eggs. This phylogenetic pattern led to the assumption that colored eggs evolved within crown birds. The mosaic evolution of supposedly avian traits in non-avian theropod dinosaurs, however, such as the supposed evolution of partially open nesting behavior in oviraptorids, argues against this long-established theory. Using a double-checking liquid chromatography ESI-Q-TOF mass spectrometry routine, we traced the origin of colored eggs to their non-avian dinosaur ancestors by providing the first record of the avian eggshell pigments protoporphyrin and biliverdin in the eggshells of Late Cretaceous oviraptorid dinosaurs. The eggshell parataxon Macroolithus yaotunensis can be assigned to the oviraptor Heyuannia huangi based on exceptionally preserved, late developmental stage embryo remains. The analyzed eggshells are from three Late Cretaceous fluvial deposits ranging from eastern to southernmost China. Reevaluation of these taphonomic settings, and a consideration of patterns in the porosity of completely preserved eggs support an at least partially open nesting behavior for oviraptorosaurs. Such a nest arrangement corresponds with our reconstruction of blue-green eggs for oviraptors. According to the sexual signaling hypothesis, the reconstructed blue-green eggs support the origin of previously hypothesized avian paternal care in oviraptorid dinosaurs. Preserved dinosaur egg color not only pushes the current limits of the vertebrate molecular and associated soft tissue fossil record, but also provides a perspective on the potential application of this unexplored paleontological resource.}, } @article {pmid28831510, year = {2017}, author = {Lefèvre, U and Cau, A and Cincotta, A and Hu, D and Chinsamy, A and Escuillié, F and Godefroit, P}, title = {A new Jurassic theropod from China documents a transitional step in the macrostructure of feathers.}, journal = {Die Naturwissenschaften}, volume = {104}, number = {9-10}, pages = {74}, pmid = {28831510}, issn = {1432-1904}, mesh = {Animals ; Biological Evolution ; Birds ; China ; Dinosaurs ; *Feathers ; Fossils ; Phylogeny ; }, abstract = {Genuine fossils with exquisitely preserved plumage from the Late Jurassic and Early Cretaceous of northeastern China have recently revealed that bird-like theropod dinosaurs had long pennaceous feathers along their hindlimbs and may have used their four wings to glide or fly. Thus, it has been postulated that early bird flight might initially have involved four wings (Xu et al. Nature 421:335-340, 2003; Hu et al. Nature 461:640-643, 2009; Han et al. Nat Commun 5:4382, 2014). Here, we describe Serikornis sungei gen. et sp. nov., a new feathered theropod from the Tiaojishan Fm (Late Jurassic) of Liaoning Province, China. Its skeletal morphology suggests a ground-dwelling ecology with no flying adaptations. Our phylogenetic analysis places Serikornis, together with other Late Jurassic paravians from China, as a basal paravians, outside the Eumaniraptora clade. The tail of Serikornis is covered proximally by filaments and distally by slender rectrices. Thin symmetrical remiges lacking barbules are attached along its forelimbs and elongate hindlimb feathers extend up to its toes, suggesting that hindlimb remiges evolved in ground-dwelling maniraptorans before being co-opted to an arboreal lifestyle or flight.}, } @article {pmid28781051, year = {2017}, author = {Brown, CM and Henderson, DM and Vinther, J and Fletcher, I and Sistiaga, A and Herrera, J and Summons, RE}, title = {An Exceptionally Preserved Three-Dimensional Armored Dinosaur Reveals Insights into Coloration and Cretaceous Predator-Prey Dynamics.}, journal = {Current biology : CB}, volume = {27}, number = {16}, pages = {2514-2521.e3}, doi = {10.1016/j.cub.2017.06.071}, pmid = {28781051}, issn = {1879-0445}, mesh = {Alberta ; Animals ; Biological Evolution ; Dinosaurs/*anatomy & histology/*physiology ; *Food Chain ; Fossils/*anatomy & histology ; *Pigmentation ; Predatory Behavior ; }, abstract = {Predator-prey dynamics are an important evolutionary driver of escalating predation mode and efficiency, and commensurate responses of prey [1-3]. Among these strategies, camouflage is important for visual concealment, with countershading the most universally observed [4-6]. Extant terrestrial herbivores free of significant predation pressure, due to large size or isolation, do not exhibit countershading. Modern predator-prey dynamics may not be directly applicable to those of the Mesozoic due to the dominance of very large, visually oriented theropod dinosaurs [7]. Despite thyreophoran dinosaurs' possessing extensive dermal armor, some of the most extreme examples of anti-predator structures [8, 9], little direct evidence of predation on these and other dinosaur megaherbivores has been documented. Here we describe a new, exquisitely three-dimensionally preserved nodosaurid ankylosaur, Borealopelta markmitchelli gen. et sp. nov., from the Early Cretaceous of Alberta, which preserves integumentary structures as organic layers, including continuous fields of epidermal scales and intact horn sheaths capping the body armor. We identify melanin in the organic residues through mass spectroscopic analyses and observe lighter pigmentation of the large parascapular spines, consistent with display, and a pattern of countershading across the body. With an estimated body mass exceeding 1,300 kg, B. markmitchelli was much larger than modern terrestrial mammals that either are countershaded or experience significant predation pressure as adults. Presence of countershading suggests predation pressure strong enough to select for concealment in this megaherbivore despite possession of massive dorsal and lateral armor, illustrating a significant dichotomy between Mesozoic predator-prey dynamics and those of modern terrestrial systems.}, } @article {pmid28603898, year = {2019}, author = {Dhouailly, D and Godefroit, P and Martin, T and Nonchev, S and Caraguel, F and Oftedal, O}, title = {Getting to the root of scales, feather and hair: As deep as odontodes?.}, journal = {Experimental dermatology}, volume = {28}, number = {4}, pages = {503-508}, doi = {10.1111/exd.13391}, pmid = {28603898}, issn = {1600-0625}, mesh = {Adaptation, Physiological ; Animal Scales/*embryology ; Animals ; *Biological Evolution ; Feathers/*embryology ; *Fossils ; Hair/*embryology ; }, abstract = {While every jawed vertebrate, or its recent ancestor, possesses teeth, skin appendages are characteristic of the living clades: skin denticles (odontodes) in chondrichthyans, dermal scales in teleosts, ducted multicellular glands in amphibians, epidermal scales in squamates, feathers in birds and hair-gland complexes in mammals, all of them showing a dense periodic patterning. While the odontode origin of teleost scales is generally accepted, the origin of both feather and hair is still debated. They appear long before mammals and birds, at least in the Jurassic in mammaliaforms and in ornithodires (pterosaurs and dinosaurs), and are contemporary to scales of early squamates. Epidermal scales might have appeared several times in evolution, and basal amniotes could not have developed a scaled dry integument, as the function of hair follicle requires its association with glands. In areas such as amnion, cornea or plantar pads, the formation of feather and hair is prevented early in embryogenesis, but can be easily reverted by playing with the Wnt/BMP/Shh pathways, which both imply the plasticity and the default competence of ectoderm. Conserved ectodermal/mesenchymal signalling pathways lead to placode formation, while later the crosstalk differs, as well as the final performing tissue(s): both epidermis and dermis for teeth and odontodes, mostly dermis for teleosts scales and only epidermis for squamate scale, feather and hair. We therefore suggest that tooth, dermal scale, epidermal scale, feather and hair evolved in parallel from a shared placode/dermal cell unit, which was present in a common ancestor, an early vertebrate gnathostome with odontodes, ca. 420 million years ago.}, } @article {pmid28542781, year = {2017}, author = {Kawabe, S and Tsunekawa, N and Kudo, K and Tirawattanawanich, C and Akishinonomiya, F and Endo, H}, title = {Morphological variation in brain through domestication of fowl.}, journal = {Journal of anatomy}, volume = {231}, number = {2}, pages = {287-297}, pmid = {28542781}, issn = {1469-7580}, mesh = {Animals ; Brain/*anatomy & histology ; Chickens/*anatomy & histology ; *Domestication ; Tomography, X-Ray Computed ; }, abstract = {Great variations in the size, shape, color, feather structure and behavior are observed among fowl breeds. Because many types of domestic fowls have been bred for various purposes, they are ideal to assess the relationship between brain morphology and avian biology. However, little is known about changes in brain shape that may have occurred during fowl domestication. We analyzed the brains of red jungle fowl and domestic fowl to clarify differences in the brain shape between these breeds, as well as the shape changes associated with size enlargement using three-dimensional geometric morphometrics. Principal component and multivariate regression analyses showed that ventrodorsal bending, anteroposterior elongation and width reduction were significantly correlated with brain size. According to the size-dependent analysis, the red jungle fowl brain has an intermediate shape between the brain of young broilers and that of large domestic fowl and adult broilers. After the size effect is removed, geometric morphometric analyses show that the brain of red jungle fowl is different from that of domestic fowl, with large round cerebral hemispheres. Significant correlations exist between the skull length and brain volume among fowl, while the brain volume relative to the skull length is distinctly larger in red jungle fowl compared with domestic fowl. The distinct brain shape and increased relative brain size of red jungle fowl may be driven by the presence of large, rounded cerebral hemispheres.}, } @article {pmid28463233, year = {2017}, author = {Xu, X and Currie, P and Pittman, M and Xing, L and Meng, Q and Lü, J and Hu, D and Yu, C}, title = {Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features.}, journal = {Nature communications}, volume = {8}, number = {}, pages = {14972}, pmid = {28463233}, issn = {2041-1723}, mesh = {Animals ; *Biological Evolution ; China ; Dinosaurs/*anatomy & histology/classification/physiology ; Extinction, Biological ; Feathers/*anatomy & histology/physiology ; Flight, Animal/physiology ; Fossils/*anatomy & histology/history ; History, Ancient ; *Phylogeny ; Software ; }, abstract = {Asymmetrical feathers have been associated with flight capability but are also found in species that do not fly, and their appearance was a major event in feather evolution. Among non-avialan theropods, they are only known in microraptorine dromaeosaurids. Here we report a new troodontid, Jianianhualong tengi gen. et sp. nov., from the Lower Cretaceous Jehol Group of China, that has anatomical features that are transitional between long-armed basal troodontids and derived short-armed ones, shedding new light on troodontid character evolution. It indicates that troodontid feathering is similar to Archaeopteryx in having large arm and leg feathers as well as frond-like tail feathering, confirming that these feathering characteristics were widely present among basal paravians. Most significantly, the taxon has the earliest known asymmetrical troodontid feathers, suggesting that feather asymmetry was ancestral to Paraves. This taxon also displays a mosaic distribution of characters like Sinusonasus, another troodontid with transitional anatomical features.}, } @article {pmid28332523, year = {2017}, author = {Padian, K}, title = {Palaeontology: Dividing the dinosaurs.}, journal = {Nature}, volume = {543}, number = {7646}, pages = {494-495}, doi = {10.1038/543494a}, pmid = {28332523}, issn = {1476-4687}, mesh = {Animals ; Biological Evolution ; Dinosaurs/*anatomy & histology ; Feathers ; Fossils ; *Paleontology ; }, } @article {pmid28324735, year = {2017}, author = {Xing, L and McKellar, RC and Xu, X and Li, G and Bai, M and Persons, WS and Miyashita, T and Benton, MJ and Zhang, J and Wolfe, AP and Yi, Q and Tseng, K and Ran, H and Currie, PJ}, title = {Response to: Phylogenetic placement, developmental trajectories and evolutionary implications of a feathered dinosaur tail in Mid-Cretaceous amber.}, journal = {Current biology : CB}, volume = {27}, number = {6}, pages = {R216-R217}, doi = {10.1016/j.cub.2017.02.023}, pmid = {28324735}, issn = {1879-0445}, mesh = {Amber ; Animals ; Dinosaurs/*anatomy & histology ; Feathers ; Fossils ; Phylogeny ; }, abstract = {In his correspondence, Markus Lambertz [1] raises some concerns about the phylogenetic placement and feather development of DIP-V-15103, the amber-entombed tail section that we recently reported [2] as fragmentary remains of a non-pygostylian coelurosaur (likely within the basal part of Coelurosauria). We here would like to respond to these concerns.}, } @article {pmid28324734, year = {2017}, author = {Lambertz, M}, title = {Phylogenetic placement, developmental trajectories and evolutionary implications of a feathered dinosaur tail in Mid-Cretaceous amber.}, journal = {Current biology : CB}, volume = {27}, number = {6}, pages = {R215-R216}, doi = {10.1016/j.cub.2017.01.029}, pmid = {28324734}, issn = {1879-0445}, mesh = {Amber ; Animals ; Biological Evolution ; China ; Dinosaurs/*anatomy & histology ; Feathers ; Fossils ; Phylogeny ; }, abstract = {In a recent report in Current Biology, Xing and colleagues [1] present a small fragment of a vertebrate tail preserved in amber that bears integumentary appendages (DIP-V-15103, Dexu Institute of Paleontology, Chaozhou, China; Figure 1). Following several analyses using cutting-edge technology the authors conclude that: the tail belongs to a non-avian theropod dinosaur (non-avialan according to the authors, but non-avian used synonymously here); the dinosaur most likely was a member of the Coelurosauria, possibly even Maniraptora; and, the integumentary appendages are feathers that support a barbule-first evolutionary pattern for feathers. DIP-V-15103 is indeed an intriguing specimen with potential implications for contributing to understanding the evolution of feathers among dinosaurs, which remains a current and undoubtedly controversial topic [2,3]. However, I would like to raise several concerns about the available evidence for the phylogenetic hypothesis concerning the placement of DIP-V-15103 as concluded by Xing and colleagues [1], and furthermore discuss the developmental trajectories predicted by them in light of their far-reaching evolutionary implications.}, } @article {pmid28165450, year = {2017}, author = {Seki, R and Li, C and Fang, Q and Hayashi, S and Egawa, S and Hu, J and Xu, L and Pan, H and Kondo, M and Sato, T and Matsubara, H and Kamiyama, N and Kitajima, K and Saito, D and Liu, Y and Gilbert, MT and Zhou, Q and Xu, X and Shiroishi, T and Irie, N and Tamura, K and Zhang, G}, title = {Functional roles of Aves class-specific cis-regulatory elements on macroevolution of bird-specific features.}, journal = {Nature communications}, volume = {8}, number = {}, pages = {14229}, pmid = {28165450}, issn = {2041-1723}, mesh = {Animals ; *Biological Evolution ; Birds/*physiology ; Datasets as Topic ; Dinosaurs/physiology ; Feathers/growth & development ; Flight, Animal/*physiology ; Gene Expression Regulation, Developmental/physiology ; Genome ; Histones/physiology ; Phylogeny ; Regulatory Sequences, Nucleic Acid/*physiology ; Transcription Factors/physiology ; Wings, Animal/*growth & development ; }, abstract = {Unlike microevolutionary processes, little is known about the genetic basis of macroevolutionary processes. One of these magnificent examples is the transition from non-avian dinosaurs to birds that has created numerous evolutionary innovations such as self-powered flight and its associated wings with flight feathers. By analysing 48 bird genomes, we identified millions of avian-specific highly conserved elements (ASHCEs) that predominantly (>99%) reside in non-coding regions. Many ASHCEs show differential histone modifications that may participate in regulation of limb development. Comparative embryonic gene expression analyses across tetrapod species suggest ASHCE-associated genes have unique roles in developing avian limbs. In particular, we demonstrate how the ASHCE driven avian-specific expression of gene Sim1 driven by ASHCE may be associated with the evolution and development of flight feathers. Together, these findings demonstrate regulatory roles of ASHCEs in the creation of avian-specific traits, and further highlight the importance of cis-regulatory rewiring during macroevolutionary changes.}, } @article {pmid28120795, year = {2016}, author = {Moyer, AE and Zheng, W and Schweitzer, MH}, title = {Microscopic and immunohistochemical analyses of the claw of the nesting dinosaur, Citipati osmolskae.}, journal = {Proceedings. Biological sciences}, volume = {283}, number = {1842}, pages = {}, pmid = {28120795}, issn = {1471-2954}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology ; Dinosaurs/*anatomy & histology ; Feathers ; Fossils ; Hoof and Claw/*anatomy & histology ; Keratins/chemistry ; }, abstract = {One of the most well-recognized Cretaceous fossils is Citipati osmolskae (MPC-D 100/979), an oviraptorid dinosaur discovered in brooding position on a nest of unhatched eggs. The original description refers to a thin lens of white material extending from a manus ungual, which was proposed to represent original keratinous claw sheath that, in life, would have covered it. Here, we test the hypothesis that this exceptional morphological preservation extends to the molecular level. The fossil sheath was compared with that of extant birds, revealing similar morphology and microstructural organization. In living birds, the claw sheath consists primarily of two structural proteins; alpha-keratin, expressed in all vertebrates, and beta-keratin, found only in reptiles and birds (sauropsids). We employed antibodies raised against avian feathers, which comprise almost entirely of beta-keratin, to demonstrate that fossil tissues respond with the same specificity, though less intensity, as those from living birds. Furthermore, we show that calcium chelation greatly increased antibody reactivity, suggesting a role for calcium in the preservation of this fossil material.}, } @article {pmid28106042, year = {2017}, author = {Li, A and Figueroa, S and Jiang, TX and Wu, P and Widelitz, R and Nie, Q and Chuong, CM}, title = {Diverse feather shape evolution enabled by coupling anisotropic signalling modules with self-organizing branching programme.}, journal = {Nature communications}, volume = {8}, number = {}, pages = {ncomms14139}, pmid = {28106042}, issn = {2041-1723}, support = {R37 AR060306/AR/NIAMS NIH HHS/United States ; T32 EB009418/EB/NIBIB NIH HHS/United States ; R01 GM107264/GM/NIGMS NIH HHS/United States ; R01 NS095355/NS/NINDS NIH HHS/United States ; R01 AR042177/AR/NIAMS NIH HHS/United States ; R01 AR047364/AR/NIAMS NIH HHS/United States ; R01 AR060306/AR/NIAMS NIH HHS/United States ; R01 DE023050/DE/NIDCR NIH HHS/United States ; P50 GM076516/GM/NIGMS NIH HHS/United States ; P30 DK048522/DK/NIDDK NIH HHS/United States ; }, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Dinosaurs ; Epithelial Cells ; Feathers/*anatomy & histology ; Growth Differentiation Factor 10/genetics ; Mesenchymal Stem Cells ; Receptors, Retinoic Acid/genetics ; Retinal Dehydrogenase/genetics ; Retinoic Acid 4-Hydroxylase/genetics ; Tretinoin/metabolism ; Wnt Proteins/genetics ; }, abstract = {Adaptation of feathered dinosaurs and Mesozoic birds to new ecological niches was potentiated by rapid diversification of feather vane shapes. The molecular mechanism driving this spectacular process remains unclear. Here, through morphology analysis, transcriptome profiling, functional perturbations and mathematical simulations, we find that mesenchyme-derived GDF10 and GREM1 are major controllers for the topologies of rachidial and barb generative zones (setting vane boundaries), respectively, by tuning the periodic-branching programme of epithelial progenitors. Their interactions with the anterior-posterior WNT gradient establish the bilateral-symmetric vane configuration. Additionally, combinatory effects of CYP26B1, CRABP1 and RALDH3 establish dynamic retinoic acid (RA) landscapes in feather mesenchyme, which modulate GREM1 expression and epithelial cell shapes. Incremental changes of RA gradient slopes establish a continuum of asymmetric flight feathers along the wing, while switch-like modulation of RA signalling confers distinct vane shapes between feather tracts. Therefore, the co-option of anisotropic signalling modules introduced new dimensions of feather shape diversification.}, } @article {pmid28071784, year = {2017}, author = {Ruxton, GD and Persons Iv, WS and Currie, PJ}, title = {A continued role for signaling functions in the early evolution of feathers.}, journal = {Evolution; international journal of organic evolution}, volume = {71}, number = {3}, pages = {797-799}, doi = {10.1111/evo.13178}, pmid = {28071784}, issn = {1558-5646}, mesh = {*Animal Communication ; Animals ; *Biological Evolution ; Birds/*physiology ; Dinosaurs/*physiology ; Feathers/*physiology ; Fossils ; Pigmentation ; *Sensation ; }, abstract = {Persons and Currie (2015) argued against either flight, thermoregulation, or signaling as a functional benefit driving the earliest evolution of feathers; rather, they favored simple feathers having an initial tactile sensory function, which changed to a thermoregulatory function as density increased. Here, we explore the relative merits of early simple feathers that may have originated as tactile sensors progressing instead toward a signaling, rather than (or in addition to) a thermoregulatory function. We suggest that signaling could act in concert with a sensory function more naturally than could thermoregulation. As such, the dismissal of a possible signaling function and the presumption that an initial sensory function led directly to a thermoregulatory function (implicit in the title "bristles before down") are premature.}, } @article {pmid27939315, year = {2016}, author = {Xing, L and McKellar, RC and Xu, X and Li, G and Bai, M and Persons, WS and Miyashita, T and Benton, MJ and Zhang, J and Wolfe, AP and Yi, Q and Tseng, K and Ran, H and Currie, PJ}, title = {A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber.}, journal = {Current biology : CB}, volume = {26}, number = {24}, pages = {3352-3360}, doi = {10.1016/j.cub.2016.10.008}, pmid = {27939315}, issn = {1879-0445}, mesh = {*Amber ; Animals ; Biological Evolution ; Dinosaurs/*anatomy & histology ; *Feathers ; *Fossils ; }, abstract = {In the two decades since the discovery of feathered dinosaurs [1-3], the range of plumage known from non-avialan theropods has expanded significantly, confirming several features predicted by developmentally informed models of feather evolution [4-10]. However, three-dimensional feather morphology and evolutionary patterns remain difficult to interpret, due to compression in sedimentary rocks [9, 11]. Recent discoveries in Cretaceous amber from Canada, France, Japan, Lebanon, Myanmar, and the United States [12-18] reveal much finer levels of structural detail, but taxonomic placement is uncertain because plumage is rarely associated with identifiable skeletal material [14]. Here we describe the feathered tail of a non-avialan theropod preserved in mid-Cretaceous (∼99 Ma) amber from Kachin State, Myanmar [17], with plumage structure that directly informs the evolutionary developmental pathway of feathers. This specimen provides an opportunity to document pristine feathers in direct association with a putative juvenile coelurosaur, preserving fine morphological details, including the spatial arrangement of follicles and feathers on the body, and micrometer-scale features of the plumage. Many feathers exhibit a short, slender rachis with alternating barbs and a uniform series of contiguous barbules, supporting the developmental hypothesis that barbs already possessed barbules when they fused to form the rachis [19]. Beneath the feathers, carbonized soft tissues offer a glimpse of preservational potential and history for the inclusion; abundant Fe[2+] suggests that vestiges of primary hemoglobin and ferritin remain trapped within the tail. The new finding highlights the unique preservation potential of amber for understanding the morphology and evolution of coelurosaurian integumentary structures.}, } @article {pmid27872291, year = {2016}, author = {Pan, Y and Zheng, W and Moyer, AE and O'Connor, JK and Wang, M and Zheng, X and Wang, X and Schroeter, ER and Zhou, Z and Schweitzer, MH}, title = {Molecular evidence of keratin and melanosomes in feathers of the Early Cretaceous bird Eoconfuciusornis.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {113}, number = {49}, pages = {E7900-E7907}, pmid = {27872291}, issn = {1091-6490}, mesh = {Animals ; Biological Evolution ; Birds/*anatomy & histology ; Feathers/*ultrastructure ; Fossils/*ultrastructure ; *Keratins ; *Melanosomes ; }, abstract = {Microbodies associated with feathers of both nonavian dinosaurs and early birds were first identified as bacteria but have been reinterpreted as melanosomes. Whereas melanosomes in modern feathers are always surrounded by and embedded in keratin, melanosomes embedded in keratin in fossils has not been demonstrated. Here we provide multiple independent molecular analyses of both microbodies and the associated matrix recovered from feathers of a new specimen of the basal bird Eoconfuciusornis from the Early Cretaceous Jehol Biota of China. Our work represents the oldest ultrastructural and immunological recognition of avian beta-keratin from an Early Cretaceous (∼130-Ma) bird. We apply immunogold to identify protein epitopes at high resolution, by localizing antibody-antigen complexes to specific fossil ultrastructures. Retention of original keratinous proteins in the matrix surrounding electron-opaque microbodies supports their assignment as melanosomes and adds to the criteria employable to distinguish melanosomes from microbial bodies. Our work sheds new light on molecular preservation within normally labile tissues preserved in fossils.}, } @article {pmid27676310, year = {2016}, author = {Gates, TA and Organ, C and Zanno, LE}, title = {Bony cranial ornamentation linked to rapid evolution of gigantic theropod dinosaurs.}, journal = {Nature communications}, volume = {7}, number = {}, pages = {12931}, pmid = {27676310}, issn = {2041-1723}, abstract = {Exaggerated cranial structures such as crests and horns, hereafter referred to collectively as ornaments, are pervasive across animal species. These structures perform vital roles in visual communication and physical interactions within and between species. Yet the origin and influence of ornamentation on speciation and ecology across macroevolutionary time scales remains poorly understood for virtually all animals. Here, we explore correlative evolution of osseous cranial ornaments with large body size in theropod dinosaurs using a phylogenetic comparative framework. We find that body size evolved directionally toward phyletic giantism an order of magnitude faster in theropod species possessing ornaments compared with unadorned lineages. In addition, we find a body mass threshold below which bony cranial ornaments do not originate. Maniraptoriform dinosaurs generally lack osseous cranial ornaments despite repeatedly crossing this body size threshold. Our study provides novel, quantitative support for a shift in selective pressures on socio-sexual display mechanisms in theropods coincident with the evolution of pennaceous feathers.}, } @article {pmid27641767, year = {2016}, author = {Vinther, J and Nicholls, R and Lautenschlager, S and Pittman, M and Kaye, TG and Rayfield, E and Mayr, G and Cuthill, IC}, title = {3D Camouflage in an Ornithischian Dinosaur.}, journal = {Current biology : CB}, volume = {26}, number = {18}, pages = {2456-2462}, pmid = {27641767}, issn = {1879-0445}, support = {BB/J002372/1//Biotechnology and Biological Sciences Research Council/United Kingdom ; }, mesh = {Animals ; *Biological Mimicry ; China ; Dinosaurs/*physiology ; Ecosystem ; *Fossils ; *Pigmentation ; }, abstract = {Countershading was one of the first proposed mechanisms of camouflage [1, 2]. A dark dorsum and light ventrum counteract the gradient created by illumination from above, obliterating cues to 3D shape [3-6]. Because the optimal countershading varies strongly with light environment [7-9], pigmentation patterns give clues to an animal's habitat. Indeed, comparative evidence from ungulates [9] shows that interspecific variation in countershading matches predictions: in open habitats, where direct overhead sunshine dominates, a sharp dark-light color transition high up the body is evident; in closed habitats (e.g., under forest canopy), diffuse illumination dominates and a smoother dorsoventral gradation is found. We can apply this approach to extinct animals in which the preservation of fossil melanin allows reconstruction of coloration [10-15]. Here we present a study of an exceptionally well-preserved specimen of Psittacosaurus sp. from the Chinese Jehol biota [16, 17]. This Psittacosaurus was countershaded [16] with a light underbelly and tail, whereas the chest was more pigmented. Other patterns resemble disruptive camouflage, whereas the chin and jugal bosses on the face appear dark. We projected the color patterns onto an anatomically accurate life-size model in order to assess their function experimentally. The patterns are compared to the predicted optimal countershading from the measured radiance patterns generated on an identical uniform gray model in direct versus diffuse illumination. These studies suggest that Psittacosaurus sp. inhabited a closed habitat such as a forest with a relatively dense canopy. VIDEO ABSTRACT.}, } @article {pmid27488652, year = {2016}, author = {Twyman, H and Valenzuela, N and Literman, R and Andersson, S and Mundy, NI}, title = {Seeing red to being red: conserved genetic mechanism for red cone oil droplets and co-option for red coloration in birds and turtles.}, journal = {Proceedings. Biological sciences}, volume = {283}, number = {1836}, pages = {}, pmid = {27488652}, issn = {1471-2954}, support = {//Biotechnology and Biological Sciences Research Council/United Kingdom ; }, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/*genetics ; Color Vision/*genetics ; Cytochrome P-450 CYP2J2 ; Cytochrome P-450 Enzyme System/*genetics ; Pigmentation ; Retina/anatomy & histology ; Retinal Cone Photoreceptor Cells/*cytology ; Turtles/anatomy & histology/*genetics ; }, abstract = {Avian ketocarotenoid pigments occur in both the red retinal oil droplets that contribute to colour vision and bright red coloration used in signalling. Turtles are the only other tetrapods with red retinal oil droplets, and some also display red carotenoid-based coloration. Recently, the CYP2J19 gene was strongly implicated in ketocarotenoid synthesis in birds. Here, we investigate CYP2J19 evolution in relation to colour vision and red coloration in reptiles using genomic and expression data. We show that turtles, but not crocodiles or lepidosaurs, possess a CYP2J19 orthologue, which arose via gene duplication before turtles and archosaurs split, and which is strongly and specifically expressed in the ketocarotenoid-containing retina and red integument. We infer that CYP2J19 initially functioned in colour vision in archelosaurs and conclude that red ketocarotenoid-based coloration evolved independently in birds and turtles via gene regulatory changes of CYP2J19 Our results suggest that red oil droplets contributed to colour vision in dinosaurs and pterosaurs.}, } @article {pmid27441115, year = {2016}, author = {Dececchi, TA and Larsson, HC and Habib, MB}, title = {The wings before the bird: an evaluation of flapping-based locomotory hypotheses in bird antecedents.}, journal = {PeerJ}, volume = {4}, number = {}, pages = {e2159}, pmid = {27441115}, issn = {2167-8359}, abstract = {BACKGROUND: Powered flight is implicated as a major driver for the success of birds. Here we examine the effectiveness of three hypothesized pathways for the evolution of the flight stroke, the forelimb motion that powers aerial locomotion, in a terrestrial setting across a range of stem and basal avians: flap running, Wing Assisted Incline Running (WAIR), and wing-assisted leaping.

METHODS: Using biomechanical mathematical models based on known aerodynamic principals and in vivo experiments and ground truthed using extant avians we seek to test if an incipient flight stroke may have contributed sufficient force to permit flap running, WAIR, or leaping takeoff along the phylogenetic lineage from Coelurosauria to birds.

RESULTS: None of these behaviours were found to meet the biomechanical threshold requirements before Paraves. Neither was there a continuous trend of refinement for any of these biomechanical performances across phylogeny nor a signal of universal applicability near the origin of birds. None of these flap-based locomotory models appear to have been a major influence on pre-flight character acquisition such as pennaceous feathers, suggesting non-locomotory behaviours, and less stringent locomotory behaviours such as balancing and braking, played a role in the evolution of the maniraptoran wing and nascent flight stroke. We find no support for widespread prevalence of WAIR in non-avian theropods, but can't reject its presence in large winged, small-bodied taxa like Microraptor and Archaeopteryx.

DISCUSSION: Using our first principles approach we find that "near flight" locomotor behaviors are most sensitive to wing area, and that non-locomotory related selection regimes likely expanded wing area well before WAIR and other such behaviors were possible in derived avians. These results suggest that investigations of the drivers for wing expansion and feather elongation in theropods need not be intrinsically linked to locomotory adaptations, and this separation is critical for our understanding of the origin of powered flight and avian evolution.}, } @article {pmid27441102, year = {2016}, author = {Prado, GM and Anelli, LE and Petri, S and Romero, GR}, title = {New occurrences of fossilized feathers: systematics and taphonomy of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil.}, journal = {PeerJ}, volume = {4}, number = {}, pages = {e1916}, pmid = {27441102}, issn = {2167-8359}, abstract = {Here we describe three fossil feathers from the Early Cretaceous Santana Formation of the Araripe Basin, Brazil. Feathers are the most complex multiform vertebrate integuments; they perform different functions, occurring in both avian and non-avian dinosaurs. Despite their rarity, fossil feathers have been found across the world. Most of the Brazilian feather fossil record comes from the Santana Formation. This formation is composed of two members: Crato (lake) and Romualdo (lagoon); both of which are predominantly reduced deposits, precluding bottom dwelling organisms, resulting in exceptional preservation of the fossils. Despite arid and hot conditions during the Cretaceous, life teemed in the adjacency of this paleolake. Feathered non-avian dinosaurs have not yet been described from the Crato Member, even though there are suggestions of their presence in nearby basins. Our description of the three feathers from the Crato laminated limestone reveals that, despite the small sample size, they can be referred to coelurosaurian theropods. Moreover, based on comparisons with extant feather morphotypes they can be identified as one contour feather and two downy feathers. Despite their rareness and low taxonomic potential, fossilized feathers can offer insights about the paleobiology of its owners and the paleoecology of the Araripe Basin.}, } @article {pmid27352215, year = {2016}, author = {Xing, L and McKellar, RC and Wang, M and Bai, M and O'Connor, JK and Benton, MJ and Zhang, J and Wang, Y and Tseng, K and Lockley, MG and Li, G and Zhang, W and Xu, X}, title = {Mummified precocial bird wings in mid-Cretaceous Burmese amber.}, journal = {Nature communications}, volume = {7}, number = {}, pages = {12089}, pmid = {27352215}, issn = {2041-1723}, mesh = {Amber ; Animals ; *Birds ; *Feathers ; *Fossils ; Pigmentation ; *Wings, Animal ; }, abstract = {Our knowledge of Cretaceous plumage is limited by the fossil record itself: compression fossils surrounding skeletons lack the finest morphological details and seldom preserve visible traces of colour, while discoveries in amber have been disassociated from their source animals. Here we report the osteology, plumage and pterylosis of two exceptionally preserved theropod wings from Burmese amber, with vestiges of soft tissues. The extremely small size and osteological development of the wings, combined with their digit proportions, strongly suggests that the remains represent precocial hatchlings of enantiornithine birds. These specimens demonstrate that the plumage types associated with modern birds were present within single individuals of Enantiornithes by the Cenomanian (99 million years ago), providing insights into plumage arrangement and microstructure alongside immature skeletal remains. This finding brings new detail to our understanding of infrequently preserved juveniles, including the first concrete examples of follicles, feather tracts and apteria in Cretaceous avialans.}, } @article {pmid27154039, year = {2017}, author = {Lovegrove, BG}, title = {A phenology of the evolution of endothermy in birds and mammals.}, journal = {Biological reviews of the Cambridge Philosophical Society}, volume = {92}, number = {2}, pages = {1213-1240}, doi = {10.1111/brv.12280}, pmid = {27154039}, issn = {1469-185X}, mesh = {Adaptation, Physiological/physiology ; Animals ; *Biological Evolution ; Birds/*classification/*physiology ; Body Temperature Regulation/*physiology ; Mammals/*classification/*physiology ; }, abstract = {Recent palaeontological data and novel physiological hypotheses now allow a timescaled reconstruction of the evolution of endothermy in birds and mammals. A three-phase iterative model describing how endothermy evolved from Permian ectothermic ancestors is presented. In Phase One I propose that the elevation of endothermy - increased metabolism and body temperature (Tb) - complemented large-body-size homeothermy during the Permian and Triassic in response to the fitness benefits of enhanced embryo development (parental care) and the activity demands of conquering dry land. I propose that Phase Two commenced in the Late Triassic and Jurassic and was marked by extreme body-size miniaturization, the evolution of enhanced body insulation (fur and feathers), increased brain size, thermoregulatory control, and increased ecomorphological diversity. I suggest that Phase Three occurred during the Cretaceous and Cenozoic and involved endothermic pulses associated with the evolution of muscle-powered flapping flight in birds, terrestrial cursoriality in mammals, and climate adaptation in response to Late Cenozoic cooling in both birds and mammals. Although the triphasic model argues for an iterative evolution of endothermy in pulses throughout the Mesozoic and Cenozoic, it is also argued that endothermy was potentially abandoned at any time that a bird or mammal did not rely upon its thermal benefits for parental care or breeding success. The abandonment would have taken the form of either hibernation or daily torpor as observed in extant endotherms. Thus torpor and hibernation are argued to be as ancient as the origins of endothermy itself, a plesiomorphic characteristic observed today in many small birds and mammals.}, } @article {pmid27112293, year = {2016}, author = {Larson, DW and Brown, CM and Evans, DC}, title = {Dental Disparity and Ecological Stability in Bird-like Dinosaurs prior to the End-Cretaceous Mass Extinction.}, journal = {Current biology : CB}, volume = {26}, number = {10}, pages = {1325-1333}, doi = {10.1016/j.cub.2016.03.039}, pmid = {27112293}, issn = {1879-0445}, mesh = {Animals ; Biodiversity ; *Biological Evolution ; Birds/*anatomy & histology ; Dinosaurs/*anatomy & histology ; *Extinction, Biological ; Fossils/*anatomy & histology ; Phylogeny ; Tooth/anatomy & histology ; }, abstract = {The causes, rate, and selectivity of the end-Cretaceous mass extinction continue to be highly debated [1-5]. Extinction patterns in small, feathered maniraptoran dinosaurs (including birds) are important for understanding extant biodiversity and present an enigma considering the survival of crown group birds (Neornithes) and the extinction of their close kin across the end-Cretaceous boundary [6]. Because of the patchy Cretaceous fossil record of small maniraptorans [7-12], this important transition has not been closely examined in this group. Here, we test the hypothesis that morphological disparity in bird-like dinosaurs was decreasing leading up to the end-Cretaceous mass extinction, as has been hypothesized in some dinosaurs [13, 14]. To test this, we examined tooth morphology, an ecological indicator in fossil reptiles [15-19], from over 3,100 maniraptoran teeth from four groups (Troodontidae, Dromaeosauridae, Richardoestesia, and cf. Aves) across the last 18 million years of the Cretaceous. We demonstrate that tooth disparity, a proxy for variation in feeding ecology, shows no significant decline leading up to the extinction event within any of the groups. Tooth morphospace occupation also remains static over this time interval except for increased size during the early Maastrichtian. Our data provide strong support that extinction within this group occurred suddenly after a prolonged period of ecological stability. To explain this sudden extinction of toothed maniraptorans and the survival of Neornithes, we propose that diet may have been an extinction filter and suggest that granivory associated with an edentulous beak was a key ecological trait in the survival of some lineages.}, } @article {pmid27100994, year = {2016}, author = {Heers, AM and Baier, DB and Jackson, BE and Dial, KP}, title = {Flapping before Flight: High Resolution, Three-Dimensional Skeletal Kinematics of Wings and Legs during Avian Development.}, journal = {PloS one}, volume = {11}, number = {4}, pages = {e0153446}, pmid = {27100994}, issn = {1932-6203}, mesh = {Animals ; Biomechanical Phenomena ; *Flight, Animal ; Galliformes/*physiology ; Leg Bones/anatomy & histology/*physiology ; Tomography, X-Ray Computed ; Wings, Animal/anatomy & histology/*physiology ; }, abstract = {Some of the greatest transformations in vertebrate history involve developmental and evolutionary origins of avian flight. Flight is the most power-demanding mode of locomotion, and volant adult birds have many anatomical features that presumably help meet these demands. However, juvenile birds, like the first winged dinosaurs, lack many hallmarks of advanced flight capacity. Instead of large wings they have small "protowings", and instead of robust, interlocking forelimb skeletons their limbs are more gracile and their joints less constrained. Such traits are often thought to preclude extinct theropods from powered flight, yet young birds with similarly rudimentary anatomies flap-run up slopes and even briefly fly, thereby challenging longstanding ideas on skeletal and feather function in the theropod-avian lineage. Though skeletons and feathers are the common link between extinct and extant theropods and figure prominently in discussions on flight performance (extant birds) and flight origins (extinct theropods), skeletal inter-workings are hidden from view and their functional relationship with aerodynamically active wings is not known. For the first time, we use X-ray Reconstruction of Moving Morphology to visualize skeletal movement in developing birds, and explore how development of the avian flight apparatus corresponds with ontogenetic trajectories in skeletal kinematics, aerodynamic performance, and the locomotor transition from pre-flight flapping behaviors to full flight capacity. Our findings reveal that developing chukars (Alectoris chukar) with rudimentary flight apparatuses acquire an "avian" flight stroke early in ontogeny, initially by using their wings and legs cooperatively and, as they acquire flight capacity, counteracting ontogenetic increases in aerodynamic output with greater skeletal channelization. In conjunction with previous work, juvenile birds thereby demonstrate that the initial function of developing wings is to enhance leg performance, and that aerodynamically active, flapping wings might better be viewed as adaptations or exaptations for enhancing leg performance.}, } @article {pmid27070583, year = {2016}, author = {Galván, I and Solano, F}, title = {Bird Integumentary Melanins: Biosynthesis, Forms, Function and Evolution.}, journal = {International journal of molecular sciences}, volume = {17}, number = {4}, pages = {520}, pmid = {27070583}, issn = {1422-0067}, mesh = {Amino Acid Sequence ; Animals ; Biological Evolution ; Birds/genetics/*physiology ; Body Temperature Regulation ; Environment ; Gene Expression Regulation ; Melanins/chemistry/genetics/*metabolism ; Signal Transduction ; }, abstract = {Melanins are the ubiquitous pigments distributed in nature. They are one of the main pigments responsible for colors in living cells. Birds are among the most diverse animals regarding melanin-based coloration, especially in the plumage, although they also pigment bare parts of the integument. This review is devoted to the main characteristics of bird melanins, including updated views of the formation and nature of melanin granules, whose interest has been raised in the last years for inferring the color of extinct birds and non-avian theropod dinosaurs using resistant fossil feathers. The molecular structure of the two main types of melanin, eumelanin and pheomelanin, and the environmental and genetic factors that regulate avian melanogenesis are also presented, establishing the main relationship between them. Finally, the special functions of melanin in bird feathers are also discussed, emphasizing the aspects more closely related to these animals, such as honest signaling, and the factors that may drive the evolution of pheomelanin and pheomelanin-based color traits, an issue for which birds have been pioneer study models.}, } @article {pmid27040775, year = {2016}, author = {McNamara, ME and Orr, PJ and Kearns, SL and Alcalá, L and Anadón, P and Peñalver, E}, title = {Reconstructing Carotenoid-Based and Structural Coloration in Fossil Skin.}, journal = {Current biology : CB}, volume = {26}, number = {8}, pages = {1075-1082}, doi = {10.1016/j.cub.2016.02.038}, pmid = {27040775}, issn = {1879-0445}, mesh = {Animals ; Carotenoids/*metabolism ; Chromatophores/physiology ; Colubridae/*physiology ; *Fossils ; Melanins/metabolism ; Skin Pigmentation/*physiology ; }, abstract = {Evidence of original coloration in fossils provides insights into the visual communication strategies used by ancient animals and the functional evolution of coloration over time [1-7]. Hitherto, all reconstructions of the colors of reptile integument and the plumage of fossil birds and feathered dinosaurs have been of melanin-based coloration [1-6]. Extant animals also use other mechanisms for producing color [8], but these have not been identified in fossils. Here we report the first examples of carotenoid-based coloration in the fossil record, and of structural coloration in fossil integument. The fossil skin, from a 10 million-year-old colubrid snake from the Late Miocene Libros Lagerstätte (Teruel, Spain) [9, 10], preserves dermal pigment cells (chromatophores)-xanthophores, iridophores, and melanophores-in calcium phosphate. Comparison with chromatophore abundance and position in extant reptiles [11-15] indicates that the fossil snake was pale-colored in ventral regions; dorsal and lateral regions were green with brown-black and yellow-green transverse blotches. Such coloration most likely functioned in substrate matching and intraspecific signaling. Skin replicated in authigenic minerals is not uncommon in exceptionally preserved fossils [16, 17], and dermal pigment cells generate coloration in numerous reptile, amphibian, and fish taxa today [18]. Our discovery thus represents a new means by which to reconstruct the original coloration of exceptionally preserved fossil vertebrates.}, } @article {pmid27014289, year = {2016}, author = {Llorente, B and D'Andrea, L and Rodríguez-Concepción, M}, title = {Evolutionary Recycling of Light Signaling Components in Fleshy Fruits: New Insights on the Role of Pigments to Monitor Ripening.}, journal = {Frontiers in plant science}, volume = {7}, number = {}, pages = {263}, pmid = {27014289}, issn = {1664-462X}, abstract = {Besides an essential source of energy, light provides environmental information to plants. Photosensory pathways are thought to have occurred early in plant evolution, probably at the time of the Archaeplastida ancestor, or perhaps even earlier. Manipulation of individual components of light perception and signaling networks in tomato (Solanum lycopersicum) affects the metabolism of ripening fruit at several levels. Most strikingly, recent experiments have shown that some of the molecular mechanisms originally devoted to sense and respond to environmental light cues have been re-adapted during evolution to provide plants with useful information on fruit ripening progression. In particular, the presence of chlorophylls in green fruit can strongly influence the spectral composition of the light filtered through the fruit pericarp. The concomitant changes in light quality can be perceived and transduced by phytochromes (PHYs) and PHY-interacting factors, respectively, to regulate gene expression and in turn modulate the production of carotenoids, a family of metabolites that are relevant for the final pigmentation of ripe fruits. We raise the hypothesis that the evolutionary recycling of light-signaling components to finely adjust pigmentation to the actual ripening stage of the fruit may have represented a selective advantage for primeval fleshy-fruited plants even before the extinction of dinosaurs.}, } @article {pmid26977633, year = {2016}, author = {Domyan, ET and Kronenberg, Z and Infante, CR and Vickrey, AI and Stringham, SA and Bruders, R and Guernsey, MW and Park, S and Payne, J and Beckstead, RB and Kardon, G and Menke, DB and Yandell, M and Shapiro, MD}, title = {Molecular shifts in limb identity underlie development of feathered feet in two domestic avian species.}, journal = {eLife}, volume = {5}, number = {}, pages = {e12115}, pmid = {26977633}, issn = {2050-084X}, support = {R01HD053728/HD/NICHD NIH HHS/United States ; R01GM104390/GM/NIGMS NIH HHS/United States ; T32GM007464/GM/NIGMS NIH HHS/United States ; F32GM103077/GM/NIGMS NIH HHS/United States ; T32HD07491/HD/NICHD NIH HHS/United States ; R01 HD053728/HD/NICHD NIH HHS/United States ; F32 GM103077/GM/NIGMS NIH HHS/United States ; R01 GM104390/GM/NIGMS NIH HHS/United States ; T32 HD007491/HD/NICHD NIH HHS/United States ; R01 GM115996/GM/NIGMS NIH HHS/United States ; T32 GM007464/GM/NIGMS NIH HHS/United States ; R01GM115996/GM/NIGMS NIH HHS/United States ; }, mesh = {Animals ; Chickens/*anatomy & histology/genetics ; Columbidae/*anatomy & histology/genetics ; *Feathers ; Forelimb/*anatomy & histology ; *Gene Expression Regulation ; Hindlimb/*anatomy & histology ; Transcription Factors/genetics ; }, abstract = {Birds display remarkable diversity in the distribution and morphology of scales and feathers on their feet, yet the genetic and developmental mechanisms governing this diversity remain unknown. Domestic pigeons have striking variation in foot feathering within a single species, providing a tractable model to investigate the molecular basis of skin appendage differences. We found that feathered feet in pigeons result from a partial transformation from hindlimb to forelimb identity mediated by cis-regulatory changes in the genes encoding the hindlimb-specific transcription factor Pitx1 and forelimb-specific transcription factor Tbx5. We also found that ectopic expression of Tbx5 is associated with foot feathers in chickens, suggesting similar molecular pathways underlie phenotypic convergence between these two species. These results show how changes in expression of regional patterning genes can generate localized changes in organ fate and morphology, and provide viable molecular mechanisms for diversity in hindlimb scale and feather distribution.}, } @article {pmid26774070, year = {2016}, author = {Turner, DD}, title = {A second look at the colors of the dinosaurs.}, journal = {Studies in history and philosophy of science}, volume = {55}, number = {}, pages = {60-68}, doi = {10.1016/j.shpsa.2015.08.012}, pmid = {26774070}, issn = {0039-3681}, mesh = {Animals ; *Color ; *Dinosaurs ; *Feathers/anatomy & histology ; Fossils ; History, Ancient ; Knowledge ; Paleontology ; Research/trends ; }, abstract = {In earlier work, I predicted that we would probably not be able to determine the colors of the dinosaurs. I lost this epistemic bet against science in dramatic fashion when scientists discovered that it is possible to draw inferences about dinosaur coloration based on the microstructure of fossil feathers (Vinther et al., 2008). This paper is an exercise in philosophical error analysis. I examine this episode with two questions in mind. First, does this case lend any support to epistemic optimism about historical science? Second, under what conditions is it rational to make predictions about what questions scientists will or will not be able answer? In reply to the first question, I argue that the recent work on the colors of the dinosaurs matters less to the debate about the epistemology of historical science than it might seem. In reply to the second question, I argue that it is difficult to specify a policy that would rule out the failed bet without also being too conservative.}, } @article {pmid26767728, year = {2016}, author = {Eliason, CM and Shawkey, MD and Clarke, JA}, title = {Evolutionary shifts in the melanin-based color system of birds.}, journal = {Evolution; international journal of organic evolution}, volume = {70}, number = {2}, pages = {445-455}, doi = {10.1111/evo.12855}, pmid = {26767728}, issn = {1558-5646}, mesh = {Animals ; Birds/*genetics ; *Evolution, Molecular ; Fossils ; Genetic Variation ; Melanins/analysis/*genetics ; Melanosomes/chemistry/genetics ; Skin Pigmentation/*genetics ; }, abstract = {Melanin pigments contained in organelles (melanosomes) impart earthy colors to feathers. Such melanin-based colors are distributed across birds and thought to be the ancestral color-producing mechanism in birds. However, we have had limited data on melanin-based color and melanosome diversity in Palaeognathae, which includes the flighted tinamous and large-bodied, flightless ratites and is the sister taxon to all other extant birds. Here, we use scanning electron microscopy and spectrophotometry to assess melanosome morphology and quantify reflected color for 19 species within this clade. We find that brown colors in ratites are uniquely associated with elongated melanosomes nearly identical in shape to those associated with black colors. Melanosome and color diversity in large-bodied ratites is limited relative to other birds (including flightless penguins) and smaller bodied basal maniraptoran dinosaur outgroups of Aves, whereas tinamous show a wider range of melanosome forms similar to neognaths. The repeated occurrence of novel melanosome forms in the nonmonophyletic ratites suggests that melanin-based color tracks changes in body size, physiology, or other life history traits associated with flight loss, but not feather morphology. We further anticipate these findings will be useful for future color reconstructions in extinct species, as variation in melanosome shape may potentially be linked to a more nuanced palette of melanin-based colors.}, } @article {pmid26754250, year = {2016}, author = {Dittmar, K and Zhu, Q and Hastriter, MW and Whiting, MF}, title = {On the probability of dinosaur fleas.}, journal = {BMC evolutionary biology}, volume = {16}, number = {}, pages = {9}, pmid = {26754250}, issn = {1471-2148}, mesh = {Animals ; Biological Evolution ; China ; Dinosaurs/*parasitology ; Female ; Fossils ; Probability ; *Siphonaptera/classification ; }, abstract = {Recently, a set of publications described flea fossils from Jurassic and Early Cretaceous geological strata in northeastern China, which were suggested to have parasitized feathered dinosaurs, pterosaurs, and early birds or mammals. In support of these fossils being fleas, a recent publication in BMC Evolutionary Biology described the extended abdomen of a female fossil specimen as due to blood feeding.We here comment on these findings, and conclude that the current interpretation of the evolutionary trajectory and ecology of these putative dinosaur fleas is based on appeal to probability, rather than evidence. Hence, their taxonomic positioning as fleas, or stem fleas, as well as their ecological classification as ectoparasites and blood feeders is not supported by currently available data.}, } @article {pmid26692172, year = {2016}, author = {Vinther, J}, title = {Fossil melanosomes or bacteria? A wealth of findings favours melanosomes: Melanin fossilises relatively readily, bacteria rarely, hence the need for clarification in the debate over the identity of microbodies in fossil animal specimens.}, journal = {BioEssays : news and reviews in molecular, cellular and developmental biology}, volume = {38}, number = {3}, pages = {220-225}, doi = {10.1002/bies.201500168}, pmid = {26692172}, issn = {1521-1878}, mesh = {Animals ; Bacteria/chemistry ; Fossils/*microbiology ; Melanosomes/chemistry ; Microbodies/chemistry ; Pigmentation ; }, abstract = {The discovery of fossil melanosomes has resulted in a wealth of research over the last 7 years, notably the reconstruction of colour in dinosaurs and fossil mammals. In spite of these discoveries some authors persist in arguing that the observed microbodies could represent preserved bacteria. They contend that bacteria fossilise easily and everywhere, which means that one can never be certain that a microbody is a melanosome without an extraordinary burden of evidence. However, this critique mischaracterises the morphological and structural evidence for interpreting microbodies as fossil melanosomes, and hence the basis for using them in reconstructing prehistoric colours. The claims for bacterial omnipresence in the fossil record are themselves not supported, thus tipping the scales strongly towards melanosomes in the bacteria-versus-melanosome controversy.}, } @article {pmid26440221, year = {2015}, author = {Navalón, G and Marugán-Lobón, J and Chiappe, LM and Luis Sanz, J and Buscalioni, ÁD}, title = {Soft-tissue and dermal arrangement in the wing of an Early Cretaceous bird: Implications for the evolution of avian flight.}, journal = {Scientific reports}, volume = {5}, number = {}, pages = {14864}, pmid = {26440221}, issn = {2045-2322}, mesh = {Animals ; *Biological Evolution ; Birds ; Feathers/*anatomy & histology/ultrastructure ; Flight, Animal/*physiology ; Fossils ; Microscopy, Electron, Transmission ; Muscles/*anatomy & histology/ultrastructure ; Phylogeny ; Skin/*anatomy & histology/ultrastructure ; Wings, Animal/*anatomy & histology/ultrastructure ; }, abstract = {Despite a wealth of fossils of Mesozoic birds revealing evidence of plumage and other soft-tissue structures, the epidermal and dermal anatomy of their wing's patagia remain largely unknown. We describe a distal forelimb of an enantiornithine bird from the Lower Cretaceous limestones of Las Hoyas, Spain, which reveals the overall morphology of the integument of the wing and other connective structures associated with the insertion of flight feathers. The integumentary anatomy, and myological and arthrological organization of the new fossil is remarkably similar to that of modern birds, in which a system of small muscles, tendons and ligaments attaches to the follicles of the remigial feathers and maintains the functional integrity of the wing during flight. The new fossil documents the oldest known occurrence of connective tissues in association with the flight feathers of birds. Furthermore, the presence of an essentially modern connective arrangement in the wing of enantiornithines supports the interpretation of these primitive birds as competent fliers.}, } @article {pmid26439352, year = {2015}, author = {Brusatte, SL and O'Connor, JK and Jarvis, ED}, title = {The Origin and Diversification of Birds.}, journal = {Current biology : CB}, volume = {25}, number = {19}, pages = {R888-98}, doi = {10.1016/j.cub.2015.08.003}, pmid = {26439352}, issn = {1879-0445}, mesh = {Animals ; Biodiversity ; *Biological Evolution ; Birds/anatomy & histology/*classification/genetics ; Dinosaurs/anatomy & histology/*classification/genetics ; Extinction, Biological ; Fossils/anatomy & histology ; Phylogeny ; }, abstract = {Birds are one of the most recognizable and diverse groups of modern vertebrates. Over the past two decades, a wealth of new fossil discoveries and phylogenetic and macroevolutionary studies has transformed our understanding of how birds originated and became so successful. Birds evolved from theropod dinosaurs during the Jurassic (around 165-150 million years ago) and their classic small, lightweight, feathered, and winged body plan was pieced together gradually over tens of millions of years of evolution rather than in one burst of innovation. Early birds diversified throughout the Jurassic and Cretaceous, becoming capable fliers with supercharged growth rates, but were decimated at the end-Cretaceous extinction alongside their close dinosaurian relatives. After the mass extinction, modern birds (members of the avian crown group) explosively diversified, culminating in more than 10,000 species distributed worldwide today.}, } @article {pmid26311035, year = {2015}, author = {Lindgren, J and Sjövall, P and Carney, RM and Cincotta, A and Uvdal, P and Hutcheson, SW and Gustafsson, O and Lefèvre, U and Escuillié, F and Heimdal, J and Engdahl, A and Gren, JA and Kear, BP and Wakamatsu, K and Yans, J and Godefroit, P}, title = {Molecular composition and ultrastructure of Jurassic paravian feathers.}, journal = {Scientific reports}, volume = {5}, number = {}, pages = {13520}, pmid = {26311035}, issn = {2045-2322}, mesh = {Animals ; Birds/*anatomy & histology ; Dinosaurs/*anatomy & histology ; Durapatite/chemistry ; Epidermis/ultrastructure ; Feathers/*ultrastructure ; Fossils ; Melanins ; Microbodies/ultrastructure ; Microscopy, Electron ; Spectrometry, Mass, Secondary Ion ; Spectrometry, X-Ray Emission ; Spectrophotometry, Infrared ; Time Factors ; }, abstract = {Feathers are amongst the most complex epidermal structures known, and they have a well-documented evolutionary trajectory across non-avian dinosaurs and basal birds. Moreover, melanosome-like microbodies preserved in association with fossil plumage have been used to reconstruct original colour, behaviour and physiology. However, these putative ancient melanosomes might alternatively represent microorganismal residues, a conflicting interpretation compounded by a lack of unambiguous chemical data. We therefore used sensitive molecular imaging, supported by multiple independent analytical tests, to demonstrate that the filamentous epidermal appendages in a new specimen of the Jurassic paravian Anchiornis comprise remnant eumelanosomes and fibril-like microstructures, preserved as endogenous eumelanin and authigenic calcium phosphate. These results provide novel insights into the early evolution of feathers at the sub-cellular level, and unequivocally determine that melanosomes can be preserved in fossil feathers.}, } @article {pmid26181289, year = {2015}, author = {Lü, J and Brusatte, SL}, title = {A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution.}, journal = {Scientific reports}, volume = {5}, number = {}, pages = {11775}, pmid = {26181289}, issn = {2045-2322}, mesh = {Animals ; *Biological Evolution ; China ; *Dinosaurs/anatomy & histology/classification/genetics ; *Feathers ; *Fossils ; Phylogeny ; *Wings, Animal ; }, abstract = {The famous 'feathered dinosaurs' from the Early Cretaceous of Liaoning Province, northeastern China, include several dromaeosaurids, which are among the closest relatives of birds. Most of these are small-bodied taxa with long arms and broad wings comprised of vaned feathers, but a single specimen (the holotype of Tianyuraptor) belongs to a much larger individual with reduced forelimbs, which unfortunately lacks any preserved integument. We describe a new specimen of large-bodied, short-armed Liaoning dromaeosaurid, which we designate as a new genus and species, Zhenyuanlong suni. The integument is well preserved and provides the first evidence of feather morphologies and distribution in a short-armed (and probably non-volant) dromaeosaurid, indicating that these rare and aberrant taxa had large wings consisting of pennaceous feathers on the arms and long pennaceous feathers on the tail very similar to their smaller and longer-armed relatives, but potentially lacked vaned feathers on the legs. Zhenyuanlong adds yet more diversity to the Liaoning dromaeosaurid fauna, helps further reveal a distinct short-armed bauplan among dromaeosaurids, and illuminates previously-unrecognized homoplasy that complicates dromaeosaurid phylogeny and suggests that the Liaoning taxa may not have formed their own clade.}, } @article {pmid26177465, year = {2015}, author = {Smith, T and Codrea, V}, title = {Red Iron-Pigmented Tooth Enamel in a Multituberculate Mammal from the Late Cretaceous Transylvanian "Haţeg Island".}, journal = {PloS one}, volume = {10}, number = {7}, pages = {e0132550}, pmid = {26177465}, issn = {1932-6203}, mesh = {Animals ; Dental Enamel/anatomy & histology/ultrastructure ; Geography ; Iron/*metabolism ; Islands ; Mammals/*anatomy & histology ; Phylogeny ; *Pigmentation ; Romania ; Time Factors ; Tooth/*anatomy & histology/ultrastructure ; }, abstract = {Mammals that inhabit islands are characterized by peculiar morphologies in comparison to their mainland relatives. Here we report the discovery of a partial skull associated with the lower jaws of a Late Cretaceous (≈70 Ma) multituberculate mammal from the Carpathian "Haţeg Island" of Transylvania, Romania. The mammal belongs to the Kogaionidae, one of the rare families that survived the Cretaceous-Paleogene mass extinction in Europe. The excellent preservation of this specimen allows for the first time description of the complete dentition of a kogaionid and demonstration that the enigmatic Barbatodon transylvanicus presents a mosaic of primitive and derived characters, and that it is phylogenetically basal among the Cimolodonta. Another peculiarity is the presence of red pigmentation in its tooth enamel. The red coloration is present on the anterior side of the incisors and on the cusps of most of the teeth. Energy-dispersive X-ray spectrometry (EDS) analysis reveals that the pigmented enamel contains iron, as in living placentals. Such a red pigmentation is known in living soricine shrews and many families of rodents, where it is thought to increase the resistance of the enamel to the abrasion that occurs during "grinding" mastication. The extended pattern of red pigment distribution in Barbatodon is more similar to that in eulipotyplan insectivores than to that in rodents and suggests a very hard diet and, importantly, demonstrates that its grasping incisors were not ever-growing. As inferred for other endemic Transylvanian vertebrates such as dwarf herbivorous dinosaurs and unusual theropod dinosaurs, insularity was probably the main factor of survival of such a primitive mammalian lineage relative to other mainland contemporaries of the Northern hemisphere.}, } @article {pmid26041865, year = {2015}, author = {Barrett, PM and Evans, DC and Campione, NE}, title = {Evolution of dinosaur epidermal structures.}, journal = {Biology letters}, volume = {11}, number = {6}, pages = {20150229}, pmid = {26041865}, issn = {1744-957X}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; Fossils/*anatomy & histology ; Integumentary System/*anatomy & histology ; Likelihood Functions ; Phylogeny ; }, abstract = {Spectacularly preserved non-avian dinosaurs with integumentary filaments/feathers have revolutionized dinosaur studies and fostered the suggestion that the dinosaur common ancestor possessed complex integumentary structures homologous to feathers. This hypothesis has major implications for interpreting dinosaur biology, but has not been tested rigorously. Using a comprehensive database of dinosaur skin traces, we apply maximum-likelihood methods to reconstruct the phylogenetic distribution of epidermal structures and interpret their evolutionary history. Most of these analyses find no compelling evidence for the appearance of protofeathers in the dinosaur common ancestor and scales are usually recovered as the plesiomorphic state, but results are sensitive to the outgroup condition in pterosaurs. Rare occurrences of ornithischian filamentous integument might represent independent acquisitions of novel epidermal structures that are not homologous with theropod feathers.}, } @article {pmid25963196, year = {2015}, author = {Musser, JM and Wagner, GP and Prum, RO}, title = {Nuclear β-catenin localization supports homology of feathers, avian scutate scales, and alligator scales in early development.}, journal = {Evolution & development}, volume = {17}, number = {3}, pages = {185-194}, doi = {10.1111/ede.12123}, pmid = {25963196}, issn = {1525-142X}, mesh = {Alligators and Crocodiles/anatomy & histology ; Animal Structures/chemistry/cytology ; Animals ; *Biological Evolution ; Birds/embryology/*genetics ; Feathers/chemistry/cytology/*embryology ; beta Catenin/*analysis ; }, abstract = {Feathers are an evolutionary novelty found in all extant birds. Despite recent progress investigating feather development and a revolution in dinosaur paleontology, the relationship of feathers to other amniote skin appendages, particularly reptile scales, remains unclear. Disagreement arises primarily from the observation that feathers and avian scutate scales exhibit an anatomical placode-defined as an epidermal thickening-in early development, whereas alligator and other avian scales do not. To investigate the homology of feathers and archosaur scales we examined patterns of nuclear β-catenin localization during early development of feathers and different bird and alligator scales. In birds, nuclear β-catenin is first localized to the feather placode, and then exhibits a dynamic pattern of localization in both epidermis and dermis of the feather bud. We found that asymmetric avian scutate scales and alligator scales share similar patterns of nuclear β-catenin localization with feathers. This supports the hypothesis that feathers, scutate scales, and alligator scales are homologous during early developmental stages, and are derived from early developmental stages of an asymmetric scale present in the archosaur ancestor. Furthermore, given that the earliest stage of β-catenin localization in feathers and archosaur scales is also found in placodes of several mammalian skin appendages, including hair and mammary glands, we hypothesize that a common skin appendage placode originated in the common ancestor of all amniotes. We suggest a skin placode should not be defined by anatomical features, but as a local, organized molecular signaling center from which an epidermal appendage develops.}, } @article {pmid25925437, year = {2015}, author = {}, title = {More on unicorns.}, journal = {Nature}, volume = {520}, number = {7549}, pages = {586}, doi = {10.1038/520586a}, pmid = {25925437}, issn = {1476-4687}, mesh = {Animals ; Birds/anatomy & histology/classification ; Body Size ; Bone and Bones/*anatomy & histology/physiology ; Dinosaurs/*anatomy & histology/*classification/physiology ; Feathers ; Fossils ; Wings, Animal/anatomy & histology ; }, } @article {pmid25924069, year = {2015}, author = {Xu, X and Zheng, X and Sullivan, C and Wang, X and Xing, L and Wang, Y and Zhang, X and O'Connor, JK and Zhang, F and Pan, Y}, title = {A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings.}, journal = {Nature}, volume = {521}, number = {7550}, pages = {70-73}, pmid = {25924069}, issn = {1476-4687}, mesh = {Animals ; Birds/classification ; China ; Dinosaurs/*anatomy & histology/*classification ; Feathers/anatomy & histology ; *Fossils ; Phylogeny ; Wings, Animal/*anatomy & histology ; }, abstract = {The wings of birds and their closest theropod relatives share a uniform fundamental architecture, with pinnate flight feathers as the key component. Here we report a new scansoriopterygid theropod, Yi qi gen. et sp. nov., based on a new specimen from the Middle-Upper Jurassic period Tiaojishan Formation of Hebei Province, China. Yi is nested phylogenetically among winged theropods but has large stiff filamentous feathers of an unusual type on both the forelimb and hindlimb. However, the filamentous feathers of Yi resemble pinnate feathers in bearing morphologically diverse melanosomes. Most surprisingly, Yi has a long rod-like bone extending from each wrist, and patches of membranous tissue preserved between the rod-like bones and the manual digits. Analogous features are unknown in any dinosaur but occur in various flying and gliding tetrapods, suggesting the intriguing possibility that Yi had membranous aerodynamic surfaces totally different from the archetypal feathered wings of birds and their closest relatives. Documentation of the unique forelimbs of Yi greatly increases the morphological disparity known to exist among dinosaurs, and highlights the extraordinary breadth and richness of the evolutionary experimentation that took place close to the origin of birds.}, } @article {pmid25854512, year = {2015}, author = {Vinther, J}, title = {A guide to the field of palaeo colour: Melanin and other pigments can fossilise: Reconstructing colour patterns from ancient organisms can give new insights to ecology and behaviour.}, journal = {BioEssays : news and reviews in molecular, cellular and developmental biology}, volume = {37}, number = {6}, pages = {643-656}, doi = {10.1002/bies.201500018}, pmid = {25854512}, issn = {1521-1878}, mesh = {Animals ; Behavior, Animal ; Fossils ; Humans ; Melanins/*analysis/physiology ; Melanosomes/physiology ; Paleontology ; *Pigmentation ; Trace Elements/analysis ; }, abstract = {Melanin, and other pigments have recently been shown to preserve over geologic time scales, and are found in several different organisms. This opens up the possibility of inferring colours and colour patterns ranging from invertebrates to feathered dinosaurs and mammals. An emerging discipline is palaeo colour: colour plays an important role in display and camouflage as well as in integumental strengthening and protection, which makes possible the hitherto difficult task of doing inferences about past ecologies, behaviours, and organismal appearance. Several studies and techniques have been presented in the last couple of years that have described ways to characterize pigment patterns. Here, I will review the available methods and the likely applications to understand past ecologies. A golden age of colourized dinosaurs and other animals is now dawning upon us, which may elucidate the nature of ancient predator prey interactions and display structures.}, } @article {pmid25824625, year = {2015}, author = {Persons, WS and Funston, GF and Currie, PJ and Norell, MA}, title = {A possible instance of sexual dimorphism in the tails of two oviraptorosaur dinosaurs.}, journal = {Scientific reports}, volume = {5}, number = {}, pages = {9472}, pmid = {25824625}, issn = {2045-2322}, mesh = {Animals ; Dinosaurs/*anatomy & histology ; Female ; Male ; *Sex Characteristics ; Spine/anatomy & histology ; Tail/*anatomy & histology ; }, abstract = {The hypothesis that oviraptorosaurs used tail-feather displays in courtship behavior previously predicted that oviraptorosaurs would be found to display sexually dimorphic caudal osteology. MPC-D 100/1002 and MPC-D 100/1127 are two specimens of the oviraptorosaur Khaan mckennai. Although similar in absolute size and in virtually all other anatomical details, the anterior haemal spines of MPC-D 100/1002 exceed those of MPC-D 100/1127 in ventral depth and develop a hitherto unreported "spearhead" shape. This dissimilarity cannot be readily explained as pathologic and is too extreme to be reasonably attributed to the amount of individual variation expected among con-specifics. Instead, this discrepancy in haemal spine morphology may be attributable to sexual dimorphism. The haemal spine form of MPC-D 100/1002 offers greater surface area for caudal muscle insertions. On this basis, MPC-D 100/1002 is regarded as most probably male, and MPC-D 100/1127 is regarded as most probably female.}, } @article {pmid25756292, year = {2015}, author = {Persons, WS and Currie, PJ}, title = {Bristles before down: a new perspective on the functional origin of feathers.}, journal = {Evolution; international journal of organic evolution}, volume = {69}, number = {4}, pages = {857-862}, doi = {10.1111/evo.12634}, pmid = {25756292}, issn = {1558-5646}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; Fossils ; Hair ; }, abstract = {Over the course of the last two decades, the understanding of the early evolution of feathers in nonavian dinosaurs has been revolutionized. It is now recognized that early feathers had a simple form comparable in general structure to the hairs of mammals. Insight into the prevalence of simple feathers throughout the dinosaur family tree has gradually arisen in tandem with the growing evidence for endothermic dinosaur metabolisms. This has led to the generally accepted opinion that the early feather coats of dinosaurs functioned as thermo insulation. However, thermo insulation is often erroneously stated to be a likely functional explanation for the origin of feathers. The problem with this explanation is that, like mammalian hair, simple feathers could serve as insulation only when present in sufficiently high concentrations. The theory therefore necessitates the origination of feathers en masse. We advocate for a novel origin theory of feathers as bristles. Bristles are facial feathers common among modern birds that function like mammalian tactile whiskers, and are frequently simple and hair-like in form. Bristles serve their role in low concentrations, and therefore offer a feasible first stage in feather evolution.}, } @article {pmid25673687, year = {2015}, author = {Feo, TJ and Field, DJ and Prum, RO}, title = {Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight.}, journal = {Proceedings. Biological sciences}, volume = {282}, number = {1803}, pages = {20142864}, pmid = {25673687}, issn = {1471-2954}, mesh = {Animals ; *Biological Evolution ; Biomechanical Phenomena ; Birds/*anatomy & histology/physiology ; Dinosaurs/anatomy & histology/physiology ; Feathers/*anatomy & histology ; *Flight, Animal ; Fossils ; Phylogeny ; }, abstract = {The geometry of feather barbs (barb length and barb angle) determines feather vane asymmetry and vane rigidity, which are both critical to a feather's aerodynamic performance. Here, we describe the relationship between barb geometry and aerodynamic function across the evolutionary history of asymmetrical flight feathers, from Mesozoic taxa outside of modern avian diversity (Microraptor, Archaeopteryx, Sapeornis, Confuciusornis and the enantiornithine Eopengornis) to an extensive sample of modern birds. Contrary to previous assumptions, we find that barb angle is not related to vane-width asymmetry; instead barb angle varies with vane function, whereas barb length variation determines vane asymmetry. We demonstrate that barb geometry significantly differs among functionally distinct portions of flight feather vanes, and that cutting-edge leading vanes occupy a distinct region of morphospace characterized by small barb angles. This cutting-edge vane morphology is ubiquitous across a phylogenetically and functionally diverse sample of modern birds and Mesozoic stem birds, revealing a fundamental aerodynamic adaptation that has persisted from the Late Jurassic. However, in Mesozoic taxa stemward of Ornithurae and Enantiornithes, trailing vane barb geometry is distinctly different from that of modern birds. In both modern birds and enantiornithines, trailing vanes have larger barb angles than in comparatively stemward taxa like Archaeopteryx, which exhibit small trailing vane barb angles. This discovery reveals a previously unrecognized evolutionary transition in flight feather morphology, which has important implications for the flight capacity of early feathered theropods such as Archaeopteryx and Microraptor. Our findings suggest that the fully modern avian flight feather, and possibly a modern capacity for powered flight, evolved crownward of Confuciusornis, long after the origin of asymmetrical flight feathers, and much later than previously recognized.}, } @article {pmid25525237, year = {2014}, author = {Koschowitz, MC and Lambertz, M and Fischer, C and Sander, PM}, title = {On the origin of feathers--response.}, journal = {Science (New York, N.Y.)}, volume = {346}, number = {6216}, pages = {1466-1467}, doi = {10.1126/science.346.6216.1466-c}, pmid = {25525237}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; *Color Vision ; Dinosaurs/*physiology ; Feathers/*physiology ; Galliformes/*physiology ; }, } @article {pmid25525236, year = {2014}, author = {Mayr, G}, title = {On the origin of feathers.}, journal = {Science (New York, N.Y.)}, volume = {346}, number = {6216}, pages = {1466}, doi = {10.1126/science.346.6216.1466-b}, pmid = {25525236}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; *Color Vision ; Dinosaurs/*physiology ; Feathers/*physiology ; Galliformes/*physiology ; }, } @article {pmid25518852, year = {2014}, author = {Lovell, PV and Wirthlin, M and Wilhelm, L and Minx, P and Lazar, NH and Carbone, L and Warren, WC and Mello, CV}, title = {Conserved syntenic clusters of protein coding genes are missing in birds.}, journal = {Genome biology}, volume = {15}, number = {12}, pages = {565}, pmid = {25518852}, issn = {1474-760X}, support = {R24 GM092842/GM/NIGMS NIH HHS/United States ; T15 LM007088/LM/NLM NIH HHS/United States ; R24-GM092842/GM/NIGMS NIH HHS/United States ; }, mesh = {Animals ; Avian Proteins/*genetics ; Birds/*classification/*genetics ; Chromosomes/genetics ; Computational Biology/methods ; Evolution, Molecular ; Gene Deletion ; Genomics/*methods ; Humans ; Lizards/genetics ; Multigene Family ; Phylogeny ; Synteny ; }, abstract = {BACKGROUND: Birds are one of the most highly successful and diverse groups of vertebrates, having evolved a number of distinct characteristics, including feathers and wings, a sturdy lightweight skeleton and unique respiratory and urinary/excretion systems. However, the genetic basis of these traits is poorly understood.

RESULTS: Using comparative genomics based on extensive searches of 60 avian genomes, we have found that birds lack approximately 274 protein coding genes that are present in the genomes of most vertebrate lineages and are for the most part organized in conserved syntenic clusters in non-avian sauropsids and in humans. These genes are located in regions associated with chromosomal rearrangements, and are largely present in crocodiles, suggesting that their loss occurred subsequent to the split of dinosaurs/birds from crocodilians. Many of these genes are associated with lethality in rodents, human genetic disorders, or biological functions targeting various tissues. Functional enrichment analysis combined with orthogroup analysis and paralog searches revealed enrichments that were shared by non-avian species, present only in birds, or shared between all species.

CONCLUSIONS: Together these results provide a clearer definition of the genetic background of extant birds, extend the findings of previous studies on missing avian genes, and provide clues about molecular events that shaped avian evolution. They also have implications for fields that largely benefit from avian studies, including development, immune system, oncogenesis, and brain function and cognition. With regards to the missing genes, birds can be considered ‘natural knockouts’ that may become invaluable model organisms for several human diseases.}, } @article {pmid25517372, year = {2014}, author = {Ksepka, DT}, title = {Evolution: a rapid flight towards birds.}, journal = {Current biology : CB}, volume = {24}, number = {21}, pages = {R1052-5}, doi = {10.1016/j.cub.2014.09.018}, pmid = {25517372}, issn = {1879-0445}, mesh = {Animals ; Birds/*anatomy & histology/*genetics ; Dinosaurs/*anatomy & histology/*genetics ; *Phylogeny ; }, abstract = {Remarkable feathered dinosaur fossils have blurred the lines between early birds and their non-avian dinosaur relatives. Rapid skeletal evolution and decreasing body size along one particular lineage of theropod dinosaurs paved the way for the spectacular radiation of birds.}, } @article {pmid25504729, year = {2014}, author = {Xu, X and Zhou, Z and Dudley, R and Mackem, S and Chuong, CM and Erickson, GM and Varricchio, DJ}, title = {An integrative approach to understanding bird origins.}, journal = {Science (New York, N.Y.)}, volume = {346}, number = {6215}, pages = {1253293}, doi = {10.1126/science.1253293}, pmid = {25504729}, issn = {1095-9203}, support = {AR 47364/AR/NIAMS NIH HHS/United States ; AR 60306/AR/NIAMS NIH HHS/United States ; }, mesh = {Animals ; *Biological Evolution ; *Birds/anatomy & histology/classification/physiology ; *Dinosaurs/classification ; Feathers/anatomy & histology ; Female ; Flight, Animal ; Fossils ; Male ; Morphogenesis ; Phylogeny ; Reproduction ; Respiratory System/anatomy & histology ; Wings, Animal/anatomy & histology ; }, abstract = {Recent discoveries of spectacular dinosaur fossils overwhelmingly support the hypothesis that birds are descended from maniraptoran theropod dinosaurs, and furthermore, demonstrate that distinctive bird characteristics such as feathers, flight, endothermic physiology, unique strategies for reproduction and growth, and a novel pulmonary system originated among Mesozoic terrestrial dinosaurs. The transition from ground-living to flight-capable theropod dinosaurs now probably represents one of the best-documented major evolutionary transitions in life history. Recent studies in developmental biology and other disciplines provide additional insights into how bird characteristics originated and evolved. The iconic features of extant birds for the most part evolved in a gradual and stepwise fashion throughout archosaur evolution. However, new data also highlight occasional bursts of morphological novelty at certain stages particularly close to the origin of birds and an unavoidable complex, mosaic evolutionary distribution of major bird characteristics on the theropod tree. Research into bird origins provides a premier example of how paleontological and neontological data can interact to reveal the complexity of major innovations, to answer key evolutionary questions, and to lead to new research directions. A better understanding of bird origins requires multifaceted and integrative approaches, yet fossils necessarily provide the final test of any evolutionary model.}, } @article {pmid25415961, year = {2015}, author = {Lowe, CB and Clarke, JA and Baker, AJ and Haussler, D and Edwards, SV}, title = {Feather development genes and associated regulatory innovation predate the origin of Dinosauria.}, journal = {Molecular biology and evolution}, volume = {32}, number = {1}, pages = {23-28}, pmid = {25415961}, issn = {1537-1719}, support = {//Howard Hughes Medical Institute/United States ; }, mesh = {Animals ; Biological Evolution ; Birds/anatomy & histology/*genetics ; Body Size ; Dinosaurs/*anatomy & histology/genetics/growth & development ; Evolution, Molecular ; Feathers/*growth & development/metabolism ; Genomics/*methods ; Insulin-Like Growth Factor Binding Protein 2/genetics ; Insulin-Like Growth Factor Binding Protein 5/genetics ; Keratins/genetics ; Mutation Rate ; Phylogeny ; *Regulatory Elements, Transcriptional ; }, abstract = {The evolution of avian feathers has recently been illuminated by fossils and the identification of genes involved in feather patterning and morphogenesis. However, molecular studies have focused mainly on protein-coding genes. Using comparative genomics and more than 600,000 conserved regulatory elements, we show that patterns of genome evolution in the vicinity of feather genes are consistent with a major role for regulatory innovation in the evolution of feathers. Rates of innovation at feather regulatory elements exhibit an extended period of innovation with peaks in the ancestors of amniotes and archosaurs. We estimate that 86% of such regulatory elements and 100% of the nonkeratin feather gene set were present prior to the origin of Dinosauria. On the branch leading to modern birds, we detect a strong signal of regulatory innovation near insulin-like growth factor binding protein (IGFBP) 2 and IGFBP5, which have roles in body size reduction, and may represent a genomic signature for the miniaturization of dinosaurian body size preceding the origin of flight.}, } @article {pmid25387232, year = {2015}, author = {Chen, CF and Foley, J and Tang, PC and Li, A and Jiang, TX and Wu, P and Widelitz, RB and Chuong, CM}, title = {Development, regeneration, and evolution of feathers.}, journal = {Annual review of animal biosciences}, volume = {3}, number = {}, pages = {169-195}, pmid = {25387232}, issn = {2165-8110}, support = {R01 AR042177/AR/NIAMS NIH HHS/United States ; R01 AR047364/AR/NIAMS NIH HHS/United States ; R01 AR060306/AR/NIAMS NIH HHS/United States ; }, mesh = {Animals ; Biological Evolution ; Birds/embryology/growth & development/physiology ; Dinosaurs/anatomy & histology ; Feathers/*embryology/*growth & development/physiology ; Fossils ; Morphogenesis ; Pigmentation ; Regeneration ; }, abstract = {The feather is a complex ectodermal organ with hierarchical branching patterns. It provides functions in endothermy, communication, and flight. Studies of feather growth, cycling, and health are of fundamental importance to avian biology and poultry science. In addition, feathers are an excellent model for morphogenesis studies because of their accessibility, and their distinct patterns can be used to assay the roles of specific molecular pathways. Here we review the progress in aspects of development, regeneration, and evolution during the past three decades. We cover the development of feather buds in chicken embryos, regenerative cycling of feather follicle stem cells, formation of barb branching patterns, emergence of intrafeather pigmentation patterns, interplay of hormones and feather growth, and the genetic identification of several feather variants. The discovery of feathered dinosaurs redefines the relationship between feathers and birds. Inspiration from biomaterials and flight research further fuels biomimetic potential of feathers as a multidisciplinary research focal point.}, } @article {pmid25342796, year = {2014}, author = {Godefroit, P and Sinitsa, SM and Dhouailly, D and Bolotsky, YL and Sizov, AV and McNamara, ME and Benton, MJ and Spagna, P}, title = {Response to Comment on "A Jurassic ornithischian dinosaur from Siberia with both feathers and scales".}, journal = {Science (New York, N.Y.)}, volume = {346}, number = {6208}, pages = {434}, doi = {10.1126/science.1260146}, pmid = {25342796}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology ; Epidermis/*anatomy & histology ; Feathers/*anatomy & histology ; }, abstract = {Lingham-Soliar questions our interpretation of integumentary structures in the Middle-Late Jurassic ornithischian dinosaur Kulindadromeus as feather-like appendages and alternatively proposes that the compound structures observed around the humerus and femur of Kulindadromeus are support fibers associated with badly degraded scales. We consider this hypothesis highly unlikely because of the taphonomy and morphology of the preserved structures.}, } @article {pmid25342795, year = {2014}, author = {Lingham-Soliar, T}, title = {Comment on "A Jurassic ornithischian dinosaur from Siberia with both feathers and scales".}, journal = {Science (New York, N.Y.)}, volume = {346}, number = {6208}, pages = {434}, doi = {10.1126/science.1259983}, pmid = {25342795}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology ; Epidermis/*anatomy & histology ; Feathers/*anatomy & histology ; }, abstract = {Godefroit et al. (Reports, 25 July 2014, p. 451) reported scales and feathers, including "basal plates," in an ornithischian dinosaur. Their arguments against the filaments being collagen fibers are not supported because of a fundamental misinterpretation of such structures and underestimation of their size. The parsimonious explanation is that the filaments are support fibers in association with badly degraded scales and that they do not represent early feather stages.}, } @article {pmid25342783, year = {2014}, author = {Koschowitz, MC and Fischer, C and Sander, M}, title = {Evolution. Beyond the rainbow.}, journal = {Science (New York, N.Y.)}, volume = {346}, number = {6208}, pages = {416-418}, doi = {10.1126/science.1258957}, pmid = {25342783}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Body Size ; *Color Vision ; Dinosaurs/anatomy & histology/classification/*physiology ; Feathers/anatomy & histology/*physiology ; Galliformes/anatomy & histology/classification/*physiology ; Phylogeny ; }, } @article {pmid25201982, year = {2014}, author = {Zheng, X and O'Connor, J and Wang, X and Wang, M and Zhang, X and Zhou, Z}, title = {On the absence of sternal elements in Anchiornis (Paraves) and Sapeornis (Aves) and the complex early evolution of the avian sternum.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {111}, number = {38}, pages = {13900-13905}, pmid = {25201982}, issn = {1091-6490}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/*physiology ; *Osteogenesis ; Sternum/anatomy & histology/*physiology ; }, abstract = {Anchiornis (Deinonychosauria: Troodontidae), the earliest known feathered dinosaur, and Sapeornis (Aves: Pygostylia), one of the basalmost Cretaceous birds, are both known from hundreds of specimens, although remarkably not one specimen preserves any sternal ossifications. We use histological analysis to confirm the absence of this element in adult specimens. Furthermore, the excellent preservation of soft-tissue structures in some specimens suggests that no chondrified sternum was present. Archaeopteryx, the oldest and most basal known bird, is known from only 10 specimens and the presence of a sternum is controversial; a chondrified sternum is widely considered to have been present. However, data from Anchiornis and Sapeornis suggest that a sternum may also have been completely absent in this important taxon, suggesting that the absence of a sternum could represent the plesiomorphic avian condition. Our discovery reveals an unexpected level of complexity in the early evolution of the avian sternum; the large amount of observable homoplasy is probably a direct result of the high degree of inherent developmental plasticity of the sternum compared with observations in other skeletal elements.}, } @article {pmid25137588, year = {2014}, author = {Zhou, Z}, title = {Dinosaur evolution: feathers up for selection.}, journal = {Current biology : CB}, volume = {24}, number = {16}, pages = {R751-3}, doi = {10.1016/j.cub.2014.07.017}, pmid = {25137588}, issn = {1879-0445}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; *Fossils ; }, abstract = {A new specimen of the early bird Archaeopteryx shows remarkable plumage preservation, including pennaceous leg feathers. But whether birds went through a four-winged stage, and in what exact functional context feathers evolved remains a matter of debate.}, } @article {pmid25061209, year = {2014}, author = {Godefroit, P and Sinitsa, SM and Dhouailly, D and Bolotsky, YL and Sizov, AV and McNamara, ME and Benton, MJ and Spagna, P}, title = {Dinosaur evolution. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales.}, journal = {Science (New York, N.Y.)}, volume = {345}, number = {6195}, pages = {451-455}, doi = {10.1126/science.1253351}, pmid = {25061209}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Bone and Bones/anatomy & histology ; Dinosaurs/*anatomy & histology ; Epidermis/*anatomy & histology ; Feathers/*anatomy & histology ; Hindlimb/anatomy & histology ; Siberia ; }, abstract = {Middle Jurassic to Early Cretaceous deposits from northeastern China have yielded varied theropod dinosaurs bearing feathers. Filamentous integumentary structures have also been described in ornithischian dinosaurs, but whether these filaments can be regarded as part of the evolutionary lineage toward feathers remains controversial. Here we describe a new basal neornithischian dinosaur from the Jurassic of Siberia with small scales around the distal hindlimb, larger imbricated scales around the tail, monofilaments around the head and the thorax, and more complex featherlike structures around the humerus, the femur, and the tibia. The discovery of these branched integumentary structures outside theropods suggests that featherlike structures coexisted with scales and were potentially widespread among the entire dinosaur clade; feathers may thus have been present in the earliest dinosaurs.}, } @article {pmid25025742, year = {2014}, author = {Han, G and Chiappe, LM and Ji, SA and Habib, M and Turner, AH and Chinsamy, A and Liu, X and Han, L}, title = {A new raptorial dinosaur with exceptionally long feathering provides insights into dromaeosaurid flight performance.}, journal = {Nature communications}, volume = {5}, number = {}, pages = {4382}, doi = {10.1038/ncomms5382}, pmid = {25025742}, issn = {2041-1723}, mesh = {Animals ; Dinosaurs/*physiology ; Feathers/physiology ; Flight, Animal/*physiology ; Fossils ; }, abstract = {Microraptorines are a group of predatory dromaeosaurid theropod dinosaurs with aerodynamic capacity. These close relatives of birds are essential for testing hypotheses explaining the origin and early evolution of avian flight. Here we describe a new 'four-winged' microraptorine, Changyuraptor yangi, from the Early Cretaceous Jehol Biota of China. With tail feathers that are nearly 30 cm long, roughly 30% the length of the skeleton, the new fossil possesses the longest known feathers for any non-avian dinosaur. Furthermore, it is the largest theropod with long, pennaceous feathers attached to the lower hind limbs (that is, 'hindwings'). The lengthy feathered tail of the new fossil provides insight into the flight performance of microraptorines and how they may have maintained aerial competency at larger body sizes. We demonstrate how the low-aspect-ratio tail of the new fossil would have acted as a pitch control structure reducing descent speed and thus playing a key role in landing.}, } @article {pmid24990749, year = {2014}, author = {Foth, C and Tischlinger, H and Rauhut, OW}, title = {New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers.}, journal = {Nature}, volume = {511}, number = {7507}, pages = {79-82}, pmid = {24990749}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; *Fossils ; Germany ; Hindlimb/anatomy & histology ; Phylogeny ; Skeleton ; Tail/anatomy & histology ; Wings, Animal/anatomy & histology ; }, abstract = {Discoveries of bird-like theropod dinosaurs and basal avialans in recent decades have helped to put the iconic 'Urvogel' Archaeopteryx into context and have yielded important new data on the origin and early evolution of feathers. However, the biological context under which pennaceous feathers evolved is still debated. Here we describe a new specimen of Archaeopteryx with extensive feather preservation, not only on the wings and tail, but also on the body and legs. The new specimen shows that the entire body was covered in pennaceous feathers, and that the hindlimbs had long, symmetrical feathers along the tibiotarsus but short feathers on the tarsometatarsus. Furthermore, the wing plumage demonstrates that several recent interpretations are problematic. An analysis of the phylogenetic distribution of pennaceous feathers on the tail, hindlimb and arms of advanced maniraptorans and basal avialans strongly indicates that these structures evolved in a functional context other than flight, most probably in relation to display, as suggested by some previous studies. Pennaceous feathers thus represented an exaptation and were later, in several lineages and following different patterns, recruited for aerodynamic functions. This indicates that the origin of flight in avialans was more complex than previously thought and might have involved several convergent achievements of aerial abilities.}, } @article {pmid24909554, year = {2014}, author = {Thomas, DB and Nascimbene, PC and Dove, CJ and Grimaldi, DA and James, HF}, title = {Seeking carotenoid pigments in amber-preserved fossil feathers.}, journal = {Scientific reports}, volume = {4}, number = {}, pages = {5226}, pmid = {24909554}, issn = {2045-2322}, mesh = {Amber/*chemistry ; Animals ; Biological Evolution ; Carotenoids/*metabolism ; Color ; Dinosaurs/*metabolism ; Feathers/*metabolism ; Fossils/*anatomy & histology ; Pigmentation/*physiology ; Preservation, Biological/methods ; }, abstract = {Plumage colours bestowed by carotenoid pigments can be important for visual communication and likely have a long evolutionary history within Aves. Discovering plumage carotenoids in fossil feathers could provide insight into the ecology of ancient birds and non-avian dinosaurs. With reference to a modern feather, we sought chemical evidence of carotenoids in six feathers preserved in amber (Miocene to mid-Cretaceous) and in a feather preserved as a compression fossil (Eocene). Evidence of melanin pigmentation and microstructure preservation was evaluated with scanning electron and light microscopies. We observed fine microstructural details including evidence for melanin pigmentation in the amber and compression fossils, but Raman spectral bands did not confirm the presence of carotenoids in them. Carotenoids may have been originally absent from these feathers or the pigments may have degraded during burial; the preservation of microstructure may suggest the former. Significantly, we show that carotenoid plumage pigments can be detected without sample destruction through an amber matrix using confocal Raman spectroscopy.}, } @article {pmid24802911, year = {2014}, author = {Benson, RB and Campione, NE and Carrano, MT and Mannion, PD and Sullivan, C and Upchurch, P and Evans, DC}, title = {Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage.}, journal = {PLoS biology}, volume = {12}, number = {5}, pages = {e1001853}, pmid = {24802911}, issn = {1545-7885}, mesh = {Adaptation, Physiological ; Animal Distribution ; Animals ; Biodiversity ; Birds/anatomy & histology/*classification/physiology ; Body Size/*physiology ; Dinosaurs/anatomy & histology/*classification/physiology ; Extinction, Biological ; Extremities/anatomy & histology/physiology ; Feathers/anatomy & histology/physiology ; *Fossils ; *Genetic Speciation ; *Phylogeny ; }, abstract = {Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages.}, } @article {pmid24710561, year = {2014}, author = {Nudds, RL}, title = {Reassessment of the wing feathers of Archaeopteryx lithographica suggests no robust evidence for the presence of elongated dorsal wing coverts.}, journal = {PloS one}, volume = {9}, number = {4}, pages = {e93963}, pmid = {24710561}, issn = {1932-6203}, mesh = {Animals ; Biological Evolution ; Dinosaurs/*anatomy & histology/physiology ; Feathers/*anatomy & histology/physiology ; Flight, Animal/*physiology ; Fossils ; Wings, Animal/*anatomy & histology/physiology ; }, abstract = {Recently it was proposed that the primary feathers of Archaeopteryx lithographica (HMN1880) were overlaid by long covert feathers, and that a multilayered feathered wing was a feature of early fossils with feathered forelimbs. The proposed long covert feathers of Archaeopteryx were previously interpreted as dorsally displaced remiges or a second set of impressions made by the wing. The following study shows that the qualitative arguments forwarded in support of the elongated covert hypothesis are neither robust nor supported quantitatively. The idea that the extant bird wing with its single layer of overlapping primaries evolved from an earlier multilayered heavily coveted feathered forelimb as seen in Anchiornis huxleyi is reasonable. At this juncture, however, it is premature to conclude unequivocally that the wing of Archaeopteryx consisted of primary feathers overlaid with elongated coverts.}, } @article {pmid24707892, year = {2014}, author = {Zhou, CF and Rabi, M and Joyce, WG}, title = {A new specimen of Manchurochelys manchoukuoensis from the Early Cretaceous Jehol Biota of Chifeng, Inner Mongolia, China and the phylogeny of Cretaceous basal eucryptodiran turtles.}, journal = {BMC evolutionary biology}, volume = {14}, number = {}, pages = {77}, pmid = {24707892}, issn = {1471-2148}, mesh = {Animal Shells ; Animals ; Bone and Bones/anatomy & histology ; China ; *Fossils ; *Phylogeny ; Turtles/*anatomy & histology/*classification ; }, abstract = {BACKGROUND: Manchurochelys manchoukuoensis is an emblematic turtle from the Cretaceous Yixian Formation of Liaoning, China, a geological rock unit that is famous for yielding perfectly preserved skeletons of fossil vertebrates, including that of feathered dinosaurs. Manchurochelys manchoukuoensis was one of the first vertebrates described from this fauna, also known as the Jehol Biota. The holotype was lost during World War II and only one additional specimen has been described since. Manchurochelys manchoukuoensis is a critical taxon for unraveling the phylogenetic relationships of Cretaceous pancryptodires from Asia, a group that is considered to be of key importance for the origin of crown-group hidden-neck turtles (Cryptodira).

RESULTS: A new specimen of Manchurochelys manchoukuoensis is described here from the Jiufotang Formation of Qilinshan, Chifeng, Inner Mongolia, China. This is the third specimen described and expands the range of this taxon from the Yixian Formation of the Fuxin-Yixian Basin in Liaoning to the Jiufotang Formation of the Chifeng-Yuanbaoshan Basin. A possible temporal extension of the range is less certain. The new finding adds to our understanding of the morphology of this taxon and invites a thorough revision of the phylogeny of Macrobaenidae, Sinemydidae, and closely allied forms.

CONCLUSIONS: Our comprehensive phylogenetic analyses of Cretaceous Asian pancryptodires yielded two main competing hypotheses: in the first these taxa form a paraphyletic grade, whereas in the second they form a monophyletic clade. The inclusion of problematic tree changing taxa, such as Panpleurodires (stem + crown side-neck turtles) has a major influence on the phylogenetic relationships of Sinemydidae and closely allied forms. Manchurochelys manchoukuoensis nests within Sinemydidae together with Sinemys spp. and Dracochelys bicuspis in the majority of our analyses.}, } @article {pmid24631266, year = {2014}, author = {Kowata, K and Nakaoka, M and Nishio, K and Fukao, A and Satoh, A and Ogoshi, M and Takahashi, S and Tsudzuki, M and Takeuchi, S}, title = {Identification of a feather β-keratin gene exclusively expressed in pennaceous barbule cells of contour feathers in chicken.}, journal = {Gene}, volume = {542}, number = {1}, pages = {23-28}, doi = {10.1016/j.gene.2014.03.027}, pmid = {24631266}, issn = {1879-0038}, mesh = {Animals ; Base Sequence ; Biological Evolution ; Chickens/*genetics ; Estradiol/pharmacology ; Feathers/*cytology/*metabolism ; Female ; *Gene Expression Regulation ; Male ; Oligonucleotide Array Sequence Analysis ; Open Reading Frames/genetics ; RNA, Messenger/biosynthesis ; Sequence Alignment ; beta-Keratins/*genetics ; }, abstract = {Feathers are elaborate skin appendages shared by birds and theropod dinosaurs that have hierarchical branching of the rachis, barbs, and barbules. Feather filaments consist of β-keratins encoded by multiple genes, most of which are located in tandem arrays on chromosomes 2, 25, and 27 in chicken. The expansion of the genes is thought to have contributed to feather evolution; however, it is unclear how the individual genes are involved in feather formation. The aim of the present study was to identify feather keratin genes involved in the formation of barbules. Using a combination of microarray analysis, reverse-transcription polymerase chain reaction, and in situ hybridization, we found an uncharacterized keratin gene on chromosome 7 that was expressed specifically in barbule cells in regenerating chicken feathers. We have named the gene barbule specific keratin 1 (BlSK1). The BlSK1 gene structure was similar to the gene structure of previously characterized feather keratin genes, and consisted of a non-coding leader exon, an intron, and an exon with an open reading frame (ORF). The ORF was predicted to encode a 98 aa long protein, which shared 59% identity with feather keratin B. Orthologs of BlSK1 were found in the genomes of other avian species, including turkey, duck, zebra finch, and flycatcher, in regions that shared synteny with chromosome 7 of chicken. Interestingly, BlSK1 was expressed in feather follicles that generated pennaceous barbules but not in follicles that generated plumulaceous barbules. These results suggested that the composition of feather keratins probably varies depending on the structure of the feather filaments and, that individual feather keratin genes may be involved in building different portions and/or types of feathers in chicken.}, } @article {pmid24595214, year = {2014}, author = {Moyer, AE and Zheng, W and Johnson, EA and Lamanna, MC and Li, DQ and Lacovara, KJ and Schweitzer, MH}, title = {Melanosomes or microbes: testing an alternative hypothesis for the origin of microbodies in fossil feathers.}, journal = {Scientific reports}, volume = {4}, number = {}, pages = {4233}, pmid = {24595214}, issn = {2045-2322}, mesh = {Animals ; Chickens ; *Feathers/ultrastructure ; *Fossils ; *Melanosomes ; Microbodies ; Microscopy, Electron, Scanning ; }, abstract = {Microbodies associated with fossil feathers, originally attributed to microbial biofilm, have been reinterpreted as melanosomes: pigment-containing, eukaryotic organelles. This interpretation generated hypotheses regarding coloration in non-avian and avian dinosaurs. Because melanosomes and microbes overlap in size, distribution and morphology, we re-evaluate both hypotheses. We compare melanosomes within feathers of extant chickens with patterns induced by microbial overgrowth on the same feathers, using scanning (SEM), field emission (FESEM) and transmission (TEM) electron microscopy. Melanosomes are always internal, embedded in a morphologically distinct keratinous matrix. Conversely, microbes grow across the surface of feathers in continuous layers, more consistent with published images from fossil feathers. We compare our results to both published literature and new data from a fossil feather ascribed to Gansus yumenensis (ANSP 23403). 'Mouldic impressions' were observed in association with both the feather and sediment grains, supporting a microbial origin. We propose criteria for distinguishing between these two microbodies.}, } @article {pmid24522537, year = {2014}, author = {Li, Q and Clarke, JA and Gao, KQ and Zhou, CF and Meng, Q and Li, D and D'Alba, L and Shawkey, MD}, title = {Melanosome evolution indicates a key physiological shift within feathered dinosaurs.}, journal = {Nature}, volume = {507}, number = {7492}, pages = {350-353}, pmid = {24522537}, issn = {1476-4687}, mesh = {Alligators and Crocodiles/anatomy & histology ; Animals ; *Biological Evolution ; Birds/anatomy & histology ; China ; Dinosaurs/*physiology ; Extinction, Biological ; *Feathers/cytology ; Fossils ; Hair Color ; Integumentary System/anatomy & histology/physiology ; Lizards/anatomy & histology ; Mammals/anatomy & histology ; Melanins/metabolism ; Melanosomes/*physiology/ultrastructure ; *Pigmentation ; Skin Pigmentation ; Turtles/anatomy & histology ; }, abstract = {Inference of colour patterning in extinct dinosaurs has been based on the relationship between the morphology of melanin-containing organelles (melanosomes) and colour in extant bird feathers. When this relationship evolved relative to the origin of feathers and other novel integumentary structures, such as hair and filamentous body covering in extinct archosaurs, has not been evaluated. Here we sample melanosomes from the integument of 181 extant amniote taxa and 13 lizard, turtle, dinosaur and pterosaur fossils from the Upper-Jurassic and Lower-Cretaceous of China. We find that in the lineage leading to birds, the observed increase in the diversity of melanosome morphologies appears abruptly, near the origin of pinnate feathers in maniraptoran dinosaurs. Similarly, mammals show an increased diversity of melanosome form compared to all ectothermic amniotes. In these two clades, mammals and maniraptoran dinosaurs including birds, melanosome form and colour are linked and colour reconstruction may be possible. By contrast, melanosomes in lizard, turtle and crocodilian skin, as well as the archosaurian filamentous body coverings (dinosaur 'protofeathers' and pterosaur 'pycnofibres'), show a limited diversity of form that is uncorrelated with colour in extant taxa. These patterns may be explained by convergent changes in the key melanocortin system of mammals and birds, which is known to affect pleiotropically both melanin-based colouration and energetic processes such as metabolic rate in vertebrates, and may therefore support a significant physiological shift in maniraptoran dinosaurs.}, } @article {pmid24482756, year = {2014}, author = {Chiappe, LM and Zhao, B and O'Connor, JK and Chunling, G and Wang, X and Habib, M and Marugan-Lobon, J and Meng, Q and Cheng, X}, title = {A new specimen of the Early Cretaceous bird Hongshanornis longicresta: insights into the aerodynamics and diet of a basal ornithuromorph.}, journal = {PeerJ}, volume = {2}, number = {}, pages = {e234}, pmid = {24482756}, issn = {2167-8359}, abstract = {The discovery of Hongshanornis longicresta, a small ornithuromorph bird with unusually long hindlimb proportions, was followed by the discovery of two closely related species, Longicrusavis houi and Parahongshanornis chaoyangensis. Together forming the Hongshanornithidae, these species reveal important information about the early diversity and morphological specialization of ornithuromorphs, the clade that contains all living birds. Here we report on a new specimen (DNHM D2945/6) referable to Hongshanornis longicresta that contributes significant information to better understand the morphology, trophic ecology, and aerodynamics of this species, as well as the taxonomy of the Hongshanornithidae. Most notable are the well-preserved wings and feathered tail of DNHM D2945/6, which afford an accurate reconstruction of aerodynamic parameters indicating that as early as 125 million years ago, basal ornithuromorphs had evolved aerodynamic surfaces comparable in size and design to those of many modern birds, and flight modes alike to those of some small living birds.}, } @article {pmid24471891, year = {2014}, author = {Puttick, MN and Thomas, GH and Benton, MJ}, title = {High rates of evolution preceded the origin of birds.}, journal = {Evolution; international journal of organic evolution}, volume = {68}, number = {5}, pages = {1497-1510}, pmid = {24471891}, issn = {1558-5646}, mesh = {Animals ; Birds/anatomy & histology/*genetics/physiology ; Dinosaurs/anatomy & histology/*genetics ; *Evolution, Molecular ; Flight, Animal ; Forelimb/anatomy & histology ; Time Factors ; }, abstract = {The origin of birds (Aves) is one of the great evolutionary transitions. Fossils show that many unique morphological features of modern birds, such as feathers, reduction in body size, and the semilunate carpal, long preceded the origin of clade Aves, but some may be unique to Aves, such as relative elongation of the forelimb. We study the evolution of body size and forelimb length across the phylogeny of coelurosaurian theropods and Mesozoic Aves. Using recently developed phylogenetic comparative methods, we find an increase in rates of body size and body size dependent forelimb evolution leading to small body size relative to forelimb length in Paraves, the wider clade comprising Aves and Deinonychosauria. The high evolutionary rates arose primarily from a reduction in body size, as there were no increased rates of forelimb evolution. In line with a recent study, we find evidence that Aves appear to have a unique relationship between body size and forelimb dimensions. Traits associated with Aves evolved before their origin, at high rates, and support the notion that numerous lineages of paravians were experimenting with different modes of flight through the Late Jurassic and Early Cretaceous.}, } @article {pmid24454820, year = {2014}, author = {Evangelista, D and Cardona, G and Guenther-Gleason, E and Huynh, T and Kwong, A and Marks, D and Ray, N and Tisbe, A and Tse, K and Koehl, M}, title = {Aerodynamic characteristics of a feathered dinosaur measured using physical models. Effects of form on static stability and control effectiveness.}, journal = {PloS one}, volume = {9}, number = {1}, pages = {e85203}, pmid = {24454820}, issn = {1932-6203}, mesh = {Animals ; *Dinosaurs ; *Feathers ; *Models, Biological ; }, abstract = {We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur, [Formula: see text]Microraptor gui, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. While [Formula: see text]M. gui lived after [Formula: see text]Archaeopteryx and likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies are tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver.}, } @article {pmid24153276, year = {2013}, author = {Switek, B}, title = {Palaeontology: The truth about T. rex.}, journal = {Nature}, volume = {502}, number = {7472}, pages = {424-426}, pmid = {24153276}, issn = {1476-4687}, mesh = {Animals ; Dinosaurs/anatomy & histology/*classification/physiology ; Feathers/anatomy & histology ; Fossils ; *Paleontology ; *Phylogeny ; Predatory Behavior ; }, } @article {pmid24048346, year = {2013}, author = {Dyke, G and de Kat, R and Palmer, C and van der Kindere, J and Naish, D and Ganapathisubramani, B}, title = {Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight.}, journal = {Nature communications}, volume = {4}, number = {}, pages = {2489}, doi = {10.1038/ncomms3489}, pmid = {24048346}, issn = {2041-1723}, mesh = {Animals ; Biological Evolution ; Biomechanical Phenomena ; Dinosaurs/*anatomy & histology/physiology ; Feathers/*anatomy & histology/physiology ; Flight, Animal ; *Fossils ; *Models, Anatomic ; Phylogeny ; Wind ; Wings, Animal/*anatomy & histology/physiology ; }, abstract = {Understanding the aerodynamic performance of feathered, non-avialan dinosaurs is critical to reconstructing the evolution of bird flight. Here we show that the Early Cretaceous five-winged paravian Microraptor is most stable when gliding at high-lift coefficients (low lift/drag ratios). Wind tunnel experiments and flight simulations show that sustaining a high-lift coefficient at the expense of high drag would have been the most efficient strategy for Microraptor when gliding from, and between, low elevations. Analyses also demonstrate that anatomically plausible changes in wing configuration and leg position would have made little difference to aerodynamic performance. Significant to the evolution of flight, we show that Microraptor did not require a sophisticated, 'modern' wing morphology to undertake effective glides. This is congruent with the fossil record and also with the hypothesis that symmetric 'flight' feathers first evolved in dinosaurs for non-aerodynamic functions, later being adapted to form lifting surfaces.}, } @article {pmid24003379, year = {2012}, author = {O'Connor, JK and Chiappe, LM and Chuong, CM and Bottjer, DJ and You, H}, title = {Homology and Potential Cellular and Molecular Mechanisms for the Development of Unique Feather Morphologies in Early Birds.}, journal = {Geosciences}, volume = {2}, number = {3}, pages = {157-177}, pmid = {24003379}, issn = {2076-3263}, support = {R01 AR047364/AR/NIAMS NIH HHS/United States ; }, abstract = {At least two lineages of Mesozoic birds are known to have possessed a distinct feather morphotype for which there is no neornithine (modern) equivalent. The early stepwise evolution of apparently modern feathers occurred within Maniraptora, basal to the avian transition, with asymmetrical pennaceous feathers suited for flight present in the most basal recognized avian, Archaeopteryx lithographica. The number of extinct primitive feather morphotypes recognized among non-avian dinosaurs continues to increase with new discoveries; some of these resemble feathers present in basal birds. As a result, feathers between phylogenetically widely separated taxa have been described as homologous. Here we examine the extinct feather morphotypes recognized within Aves and compare these structures with those found in non-avian dinosaurs. We conclude that the "rachis dominated" tail feathers of Confuciusornis sanctus and some enantiornithines are not equivalent to the "proximally ribbon-like" pennaceous feathers of the juvenile oviraptorosaur Similicaudipteryx yixianensis. Close morphological analysis of these unusual rectrices in basal birds supports the interpretation that they are modified pennaceous feathers. Because this feather morphotype is not seen in living birds, we build on current understanding of modern feather molecular morphogenesis to suggest a hypothetical molecular developmental model for the formation of the rachis dominated feathers of extinct basal birds.}, } @article {pmid23975643, year = {2013}, author = {Ibrahim, N and Kutschera, U}, title = {The ornithologist Alfred Russel Wallace and the controversy surrounding the dinosaurian origin of birds.}, journal = {Theory in biosciences = Theorie in den Biowissenschaften}, volume = {132}, number = {4}, pages = {267-275}, pmid = {23975643}, issn = {1611-7530}, mesh = {Animals ; *Biological Evolution ; Biology/*history ; Birds/*physiology ; Dinosaurs/*physiology ; Dissent and Disputes ; *Famous Persons ; Feathers ; Flight, Animal ; Fossils ; History, 19th Century ; }, abstract = {Over many years of his life, the British naturalist Alfred Russel Wallace (1823-1913) explored the tropical forests of Malaysia, collecting numerous specimens, including hundreds of birds, many of them new to science. Subsequently, Wallace published a series of papers on systematic ornithology, and discovered a new species on top of a volcano on Ternate, where he wrote, in 1858, his famous essay on natural selection. Based on this hands-on experience, and an analysis of an Archaeopteryx fossil, Wallace suggested that birds may have descended from dinosaurian ancestors. Here, we describe the "dinosaur-bird hypothesis" that originated with the work of Thomas H. Huxley (1825-1895). We present the strong evidence linking theropod dinosaurs to birds, and briefly outline the long and ongoing controversy around this concept. Dinosaurs preserving plumage, nesting sites and trace fossils provide overwhelming evidence for the dinosaurian origin of birds. Based on these recent findings of paleontological research, we conclude that extant birds indeed descended, with some modifications, from small, Mesozoic theropod dinosaurs. In the light of Wallace's view of bird origins, we critically evaluate recent opposing views to this idea, including Ernst Mayr's (1904-2005) arguments against the "dinosaur-bird hypothesis", and document that this famous ornithologist was not correct in his assessment of this important aspect of vertebrate evolution.}, } @article {pmid23933721, year = {2013}, author = {Clarke, A}, title = {Dinosaur energetics: setting the bounds on feasible physiologies and ecologies.}, journal = {The American naturalist}, volume = {182}, number = {3}, pages = {283-297}, doi = {10.1086/671259}, pmid = {23933721}, issn = {1537-5323}, mesh = {Animals ; Cell Respiration ; Dinosaurs/growth & development/*metabolism ; *Energy Metabolism ; Feasibility Studies ; Locomotion ; *Models, Biological ; }, abstract = {The metabolic status of dinosaurs has long been debated but remains unresolved as no consistent picture has emerged from a range of anatomical and isotopic evidence. Quantitative analysis of dinosaur energetics, based on general principles applicable to all vertebrates, shows that many features of dinosaur lifestyle are compatible with a physiology similar to that of extant lizards, scaled up to dinosaur body masses and temperatures. The analysis suggests that sufficient metabolic scope would have been available to support observed dinosaur growth rates and allow considerable locomotor activity, perhaps even migration. Since at least one dinosaur lineage evolved true endothermy, this study emphasizes there was no single dinosaur physiology. Many small theropods were insulated with feathers and appear to have been partial or full endotherms. Uninsulated small taxa, and all juveniles, presumably would have been ectothermic, with consequent diurnal and seasonal variations in body temperature. In larger taxa, inertial homeothermy would have resulted in warm and stable body temperatures but with a basal metabolism significantly below that of extant mammals or birds of the same size. It would appear that dinosaurs exhibited a range of metabolic levels to match the broad spectrum of ecological niches they occupied.}, } @article {pmid23903660, year = {2013}, author = {Balanoff, AM and Bever, GS and Rowe, TB and Norell, MA}, title = {Evolutionary origins of the avian brain.}, journal = {Nature}, volume = {501}, number = {7465}, pages = {93-96}, pmid = {23903660}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Body Weight ; Brain/*anatomy & histology ; Dinosaurs/anatomy & histology/physiology ; Feathers ; Flight, Animal ; Organ Size ; Phylogeny ; Principal Component Analysis ; Skull/anatomy & histology ; }, abstract = {Features that were once considered exclusive to modern birds, such as feathers and a furcula, are now known to have first appeared in non-avian dinosaurs. However, relatively little is known of the early evolutionary history of the hyperinflated brain that distinguishes birds from other living reptiles and provides the important neurological capablities required by flight. Here we use high-resolution computed tomography to estimate and compare cranial volumes of extant birds, the early avialan Archaeopteryx lithographica, and a number of non-avian maniraptoran dinosaurs that are phylogenetically close to the origins of both Avialae and avian flight. Previous work established that avian cerebral expansion began early in theropod history and that the cranial cavity of Archaeopteryx was volumetrically intermediate between these early forms and modern birds. Our new data indicate that the relative size of the cranial cavity of Archaeopteryx is reflective of a more generalized maniraptoran volumetric signature and in several instances is actually smaller than that of other non-avian dinosaurs. Thus, bird-like encephalization indices evolved multiple times, supporting the conclusion that if Archaeopteryx had the neurological capabilities required of flight, so did at least some other non-avian maniraptorans. This is congruent with recent findings that avialans were not unique among maniraptorans in their ability to fly in some form.}, } @article {pmid23888864, year = {2013}, author = {Xing, L and Persons, WS and Bell, PR and Xu, X and Zhang, J and Miyashita, T and Wang, F and Currie, PJ}, title = {Piscivory in the feathered dinosaur Microraptor.}, journal = {Evolution; international journal of organic evolution}, volume = {67}, number = {8}, pages = {2441-2445}, doi = {10.1111/evo.12119}, pmid = {23888864}, issn = {1558-5646}, mesh = {Animals ; Diet ; Dinosaurs/anatomy & histology/classification/*physiology ; Ecosystem ; Feathers/anatomy & histology ; *Fossils ; }, abstract = {The largest specimen of the four-winged dromaeosaurid dinosaur Microraptor gui includes preserved gut contents. Previous reports of gut contents and considerations of functional morphology have indicated that Microraptor hunted in an arboreal environment. The new specimen demonstrates that this was not strictly the case, and offers unique insights into the ecology of nonavian dinosaurs early in the evolution of flight. The preserved gut contents are composed of teleost fish remains. Several morphological adaptations of Microraptor are identified as consistent with a partially piscivorous diet, including dentition with reduced serrations and forward projecting teeth on the anterior of the dentary. The feeding habits of Microraptor can now be understood better than that of any other carnivorous nonavian dinosaur, and Microraptor appears to have been an opportunistic and generalist feeder, able to exploit the most common prey in both the arboreal and aquatic microhabitats of the Early Cretaceous Jehol ecosystem.}, } @article {pmid23744916, year = {2013}, author = {Balter, M}, title = {Paleontology. Authenticity of China's fabulous fossils gets new scrutiny.}, journal = {Science (New York, N.Y.)}, volume = {340}, number = {6137}, pages = {1153-1154}, doi = {10.1126/science.340.6137.1153}, pmid = {23744916}, issn = {1095-9203}, mesh = {Animals ; China ; *Dinosaurs ; Feathers ; *Fossils ; }, } @article {pmid23719374, year = {2013}, author = {Godefroit, P and Cau, A and Dong-Yu, H and Escuillié, F and Wenhao, W and Dyke, G}, title = {A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds.}, journal = {Nature}, volume = {498}, number = {7454}, pages = {359-362}, pmid = {23719374}, issn = {1476-4687}, mesh = {Animals ; Birds/anatomy & histology/*classification ; China ; Dinosaurs/anatomy & histology/*classification ; Feathers/anatomy & histology ; *Fossils ; *Phylogeny ; Skeleton ; }, abstract = {The recent discovery of small paravian theropod dinosaurs with well-preserved feathers in the Middle-Late Jurassic Tiaojishan Formation of Liaoning Province (northeastern China) has challenged the pivotal position of Archaeopteryx, regarded from its discovery to be the most basal bird. Removing Archaeopteryx from the base of Avialae to nest within Deinonychosauria implies that typical bird flight, powered by the forelimbs only, either evolved at least twice, or was subsequently lost or modified in some deinonychosaurians. Here we describe the complete skeleton of a new paravian from the Tiaojishan Formation of Liaoning Province, China. Including this new taxon in a comprehensive phylogenetic analysis for basal Paraves does the following: (1) it recovers it as the basal-most avialan; (2) it confirms the avialan status of Archaeopteryx; (3) it places Troodontidae as the sister-group to Avialae; (4) it supports a single origin of powered flight within Paraves; and (5) it implies that the early diversification of Paraves and Avialae took place in the Middle-Late Jurassic period.}, } @article {pmid23690987, year = {2013}, author = {Pittman, M and Gatesy, SM and Upchurch, P and Goswami, A and Hutchinson, JR}, title = {Shake a tail feather: the evolution of the theropod tail into a stiff aerodynamic surface.}, journal = {PloS one}, volume = {8}, number = {5}, pages = {e63115}, pmid = {23690987}, issn = {1932-6203}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology/classification ; Feathers/*anatomy & histology ; Phylogeny ; Principal Component Analysis ; }, abstract = {Theropod dinosaurs show striking morphological and functional tail variation; e.g., a long, robust, basal theropod tail used for counterbalance, or a short, modern avian tail used as an aerodynamic surface. We used a quantitative morphological and functional analysis to reconstruct intervertebral joint stiffness in the tail along the theropod lineage to extant birds. This provides new details of the tail's morphological transformation, and for the first time quantitatively evaluates its biomechanical consequences. We observe that both dorsoventral and lateral joint stiffness decreased along the non-avian theropod lineage (between nodes Theropoda and Paraves). Our results show how the tail structure of non-avian theropods was mechanically appropriate for holding itself up against gravity and maintaining passive balance. However, as dorsoventral and lateral joint stiffness decreased, the tail may have become more effective for dynamically maintaining balance. This supports our hypothesis of a reduction of dorsoventral and lateral joint stiffness in shorter tails. Along the avian theropod lineage (Avialae to crown group birds), dorsoventral and lateral joint stiffness increased overall, which appears to contradict our null expectation. We infer that this departure in joint stiffness is specific to the tail's aerodynamic role and the functional constraints imposed by it. Increased dorsoventral and lateral joint stiffness may have facilitated a gradually improved capacity to lift, depress, and swing the tail. The associated morphological changes should have resulted in a tail capable of producing larger muscular forces to utilise larger lift forces in flight. Improved joint mobility in neornithine birds potentially permitted an increase in the range of lift force vector orientations, which might have improved flight proficiency and manoeuvrability. The tail morphology of modern birds with tail fanning capabilities originated in early ornithuromorph birds. Hence, these capabilities should have been present in the early Cretaceous, with incipient tail-fanning capacity in the earliest pygostylian birds.}, } @article {pmid23671596, year = {2013}, author = {Gao, T and Shih, C and Rasnitsyn, AP and Ren, D}, title = {Hoplitolyda duolunica gen. et sp. nov. (Insecta, Hymenoptera, Praesiricidae), the Hitherto largest sawfly from the Mesozoic of China.}, journal = {PloS one}, volume = {8}, number = {5}, pages = {e62420}, pmid = {23671596}, issn = {1932-6203}, mesh = {Animals ; China ; Extremities/anatomy & histology ; Fossils ; Head/anatomy & histology ; Hymenoptera/*anatomy & histology ; Thorax/anatomy & histology ; Wings, Animal/anatomy & histology ; }, abstract = {BACKGROUND: Large body size of an insect, in general, enhances its capability of predation, competition, and defense, resulting in better survivability and reproduction. Hymenopterans, most being phytophagous or parasitic, have a relatively small to medium body size, typically under 50.0 mm in body length.

PRINCIPAL FINDINGS: Herein, we describe Hoplitolyda duolunica gen. et sp. nov., assigned to Praesiricidae, from the Early Cretaceous Yixian Formation of China. This new species is the largest fossil hymenopteran hitherto with body estimated >55.0 mm long and wing span >92.0 mm. H. duolunica is, to our knowledge, the only sawfly with Sc present in the hind wing but not in the forewing. Its Rs1 and M1 meeting each other at 145° angle represents an intermediate in the transition from "Y" to "T" shapes. Even though Hoplitolyda differs significantly from all previously described genera in two subfamilies of Praesricidae, we leave the new genus unplaced in existing subfamilies, pending discovery of material with more taxonomic structure.

CONCLUSIONS/SIGNIFICANCE: Hoplitolyda has many unique and interesting characters which might have benefitted its competition, survival, and reproduction: large body size and head with robust and strong mandibles for defense and/or sexual selection, unique wing venation and setal arrangements for flight capability and mobility, dense hairs on body and legs for sensing and protection, etc. Considering the reported ferocious predators of feathered dinosaurs, pterosaurs, birds, and mammals coexisting in the same eco-system, Hoplitolyda is an interesting case of "survival of the fittest" in facing its evolutionary challenges.}, } @article {pmid23661746, year = {2013}, author = {Clarke, J}, title = {Paleontology. Feathers before flight.}, journal = {Science (New York, N.Y.)}, volume = {340}, number = {6133}, pages = {690-692}, doi = {10.1126/science.1235463}, pmid = {23661746}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/growth & development ; Dinosaurs/anatomy & histology/growth & development ; Feathers/anatomy & histology/*growth & development/ultrastructure ; *Flight, Animal ; *Fossils ; Protein Structure, Secondary ; beta-Keratins/chemistry ; }, } @article {pmid23615616, year = {2013}, author = {Allen, V and Bates, KT and Li, Z and Hutchinson, JR}, title = {Linking the evolution of body shape and locomotor biomechanics in bird-line archosaurs.}, journal = {Nature}, volume = {497}, number = {7447}, pages = {104-107}, pmid = {23615616}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; Biomechanical Phenomena ; Birds/*anatomy & histology/*physiology ; Dinosaurs/*anatomy & histology/*physiology ; Feathers ; Flight, Animal ; Hindlimb/anatomy & histology/physiology ; Locomotion/*physiology ; Models, Anatomic ; Models, Biological ; Phylogeny ; }, abstract = {Locomotion in living birds (Neornithes) has two remarkable features: feather-assisted flight, and the use of unusually crouched hindlimbs for bipedal support and movement. When and how these defining functional traits evolved remains controversial. However, the advent of computer modelling approaches and the discoveries of exceptionally preserved key specimens now make it possible to use quantitative data on whole-body morphology to address the biomechanics underlying this issue. Here we use digital body reconstructions to quantify evolutionary trends in locomotor biomechanics (whole-body proportions and centre-of-mass position) across the clade Archosauria. We use three-dimensional digital reconstruction to estimate body shape from skeletal dimensions for 17 archosaurs along the ancestral bird line, including the exceptionally preserved, feathered taxa Microraptor, Archaeopteryx, Pengornis and Yixianornis, which represent key stages in the evolution of the avian body plan. Rather than a discrete transition from more-upright postures in the basal-most birds (Avialae) and their immediate outgroup deinonychosauria, our results support hypotheses of a gradual, stepwise acquisition of more-crouched limb postures across much of theropod evolution, although we find evidence of an accelerated change within the clade Maniraptora (birds and their closest relatives, such as deinonychosaurs). In addition, whereas reduction of the tail is widely accepted to be the primary morphological factor correlated with centre-of-mass position and, hence, evolution of hindlimb posture, we instead find that enlargement of the pectoral limb and several associated trends have a much stronger influence. Intriguingly, our support for the onset of accelerated morpho-functional trends within Maniraptora is closely correlated with the evolution of flight. Because we find that the evolution of enlarged forelimbs is strongly linked, via whole-body centre of mass, to hindlimb function during terrestrial locomotion, we suggest that the evolution of avian flight is linked to anatomical novelties in the pelvic limb as well as the pectoral.}, } @article {pmid23555675, year = {2013}, author = {Field, DJ and D'Alba, L and Vinther, J and Webb, SM and Gearty, W and Shawkey, MD}, title = {Melanin concentration gradients in modern and fossil feathers.}, journal = {PloS one}, volume = {8}, number = {3}, pages = {e59451}, pmid = {23555675}, issn = {1932-6203}, mesh = {Animals ; Birds/anatomy & histology/metabolism ; Feathers/anatomy & histology/cytology/*metabolism ; *Fossils ; Melanins/*metabolism ; Melanosomes/metabolism ; Pigmentation ; }, abstract = {In birds and feathered non-avian dinosaurs, within-feather pigmentation patterns range from discrete spots and stripes to more subtle patterns, but the latter remain largely unstudied. A ∼55 million year old fossil contour feather with a dark distal tip grading into a lighter base was recovered from the Fur Formation in Denmark. SEM and synchrotron-based trace metal mapping confirmed that this gradient was caused by differential concentration of melanin. To assess the potential ecological and phylogenetic prevalence of this pattern, we evaluated 321 modern samples from 18 orders within Aves. We observed that the pattern was found most frequently in distantly related groups that share aquatic ecologies (e.g. waterfowl Anseriformes, penguins Sphenisciformes), suggesting a potential adaptive function with ancient origins.}, } @article {pmid23536445, year = {2013}, author = {McNamara, ME and Briggs, DE and Orr, PJ and Field, DJ and Wang, Z}, title = {Experimental maturation of feathers: implications for reconstructions of fossil feather colour.}, journal = {Biology letters}, volume = {9}, number = {3}, pages = {20130184}, pmid = {23536445}, issn = {1744-957X}, mesh = {Animals ; *Color ; *Feathers ; *Fossils ; }, abstract = {Fossil feathers often preserve evidence of melanosomes-micrometre-scale melanin-bearing organelles that have been used to infer original colours and patterns of the plumage of dinosaurs. Such reconstructions acknowledge that evidence from other colour-producing mechanisms is presently elusive and assume that melanosome geometry is not altered during fossilization. Here, we provide the first test of this assumption, using high pressure-high temperature autoclave experiments on modern feathers to simulate the effects of burial on feather colour. Our experiments show that melanosomes are retained despite loss of visual evidence of colour and complete degradation of other colour-producing structures (e.g. quasi-ordered arrays in barbs and the keratin cortex in barbules). Significantly, however, melanosome geometry and spatial distribution are altered by the effects of pressure and temperature. These results demonstrate that reconstructions of original plumage coloration in fossils where preserved features of melanosomes are affected by diagenesis should be treated with caution. Reconstructions of fossil feather colour require assessment of the extent of preservation of various colour-producing mechanisms, and, critically, the extent of alteration of melanosome geometry.}, } @article {pmid23426262, year = {2013}, author = {Huang, D and Nel, A and Cai, C and Lin, Q and Engel, MS}, title = {Amphibious flies and paedomorphism in the Jurassic period.}, journal = {Nature}, volume = {495}, number = {7439}, pages = {94-97}, pmid = {23426262}, issn = {1476-4687}, mesh = {Animals ; Aquatic Organisms/physiology ; China ; Dinosaurs/parasitology ; Diptera/*anatomy & histology/growth & development/*physiology ; Female ; *Fossils ; *Freshwater Biology ; Gills ; Larva ; Male ; *Models, Biological ; Sexual Behavior, Animal ; Wings, Animal ; }, abstract = {The species of the Strashilidae (strashilids) have been the most perplexing of fossil insects from the Jurassic period of Russia and China. They have been widely considered to be ectoparasites of pterosaurs or feathered dinosaurs, based on the putative presence of piercing and sucking mouthparts and hind tibio-basitarsal pincers purportedly used to fix onto the host's hairs or feathers. Both the supposed host and parasite occur in the Daohugou beds from the Middle Jurassic epoch of China (approximately 165 million years ago). Here we analyse the morphology of strashilids from the Daohugou beds, and reach markedly different conclusions; namely that strashilids are highly specialized flies (Diptera) bearing large membranous wings, with substantial sexual dimorphism of the hind legs and abdominal extensions. The idea that they belong to an extinct order is unsupported, and the lineage can be placed within the true flies. In terms of major morphological and inferred behavioural features, strashilids resemble the recent (extant) and relict members of the aquatic fly family Nymphomyiidae. Their ontogeny are distinguished by the persistence in adult males of larval abdominal respiratory gills, representing a unique case of paedomorphism among endopterygote insects. Adult strashilids were probably aquatic or amphibious, shedding their wings after emergence and mating in the water.}, } @article {pmid23340434, year = {2013}, author = {Godefroit, P and Demuynck, H and Dyke, G and Hu, D and Escuillié, F and Claeys, P}, title = {Reduced plumage and flight ability of a new Jurassic paravian theropod from China.}, journal = {Nature communications}, volume = {4}, number = {}, pages = {1394}, pmid = {23340434}, issn = {2041-1723}, mesh = {Animals ; Bone and Bones/anatomy & histology ; China ; Dinosaurs/*anatomy & histology/classification/*physiology ; Feathers/*anatomy & histology ; Flight, Animal/*physiology ; Fossils ; Paleontology ; Phylogeny ; Time Factors ; }, abstract = {Feathered theropods were diverse in the Early Cretaceous Jehol Group of western Liaoning Province, China. Recently, anatomically distinct feathered taxa have been discovered in the older Middle-Late Jurassic Tiaojishan Formation in the same region. Phylogenetic hypotheses including these specimens have challenged the pivotal position of Archaeopteryx in bird phylogeny. Here we report a basal troodontid from the Tiaojishan Formation that resembles Anchiornis, also from Jianchang County (regarded as sister-taxa). The feathers of Eosinopteryx are less extensive on the limbs and tail than Anchiornis and other deinonychosaurians. With reduced plumage and short uncurved pedal claws, Eosinopteryx would have been able to run unimpeded (with large foot remiges cursorial locomotion was likely problematic for Anchiornis). Eosinopteryx increases the known diversity of small-bodied dinosaurs in the Jurassic, shows that taxa with similar body plans could occupy different niches in the same ecosystem and suggests a more complex picture for the origin of flight.}, } @article {pmid23177480, year = {2012}, author = {Longrich, NR and Vinther, J and Meng, Q and Li, Q and Russell, AP}, title = {Primitive wing feather arrangement in Archaeopteryx lithographica and Anchiornis huxleyi.}, journal = {Current biology : CB}, volume = {22}, number = {23}, pages = {2262-2267}, doi = {10.1016/j.cub.2012.09.052}, pmid = {23177480}, issn = {1879-0445}, mesh = {Animals ; Biological Evolution ; Birds/*anatomy & histology/physiology ; Dinosaurs/*anatomy & histology/physiology ; *Feathers ; *Fossils ; Wings, Animal/*anatomy & histology/physiology ; }, abstract = {In modern birds (Neornithes), the wing is composed of a layer of long, asymmetrical flight feathers overlain by short covert feathers. It has generally been assumed that wing feathers in the Jurassic bird Archaeopteryx and Cretaceous feathered dinosaurs had the same arrangement. Here, we redescribe the wings of the archaic bird Archaeopteryx lithographica and the dinosaur Anchiornis huxleyi and show that their wings differ from those of Neornithes in being composed of multiple layers of feathers. In Archaeopteryx, primaries are overlapped by long dorsal and ventral coverts. Anchiornis has a similar configuration but is more primitive in having short, slender, symmetrical remiges. Archaeopteryx and Anchiornis therefore appear to represent early experiments in the evolution of the wing. This primitive configuration has important functional implications: although the slender feather shafts of Archaeopteryx and Anchiornis make individual feathers weak, layering of the wing feathers may have produced a strong airfoil. Furthermore, the layered arrangement may have prevented the feathers from forming a slotted tip or separating to reduce drag on the upstroke. The wings of early birds therefore may have lacked the range of functions seen in Neornithes, limiting their flight ability.}, } @article {pmid23118159, year = {2012}, author = {Balter, M}, title = {Paleontology. Flying dinos and baby birds offer new clues about how avians took wing.}, journal = {Science (New York, N.Y.)}, volume = {338}, number = {6107}, pages = {591-592}, doi = {10.1126/science.338.6107.591}, pmid = {23118159}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; *Birds/anatomy & histology/growth & development/physiology ; Computer Simulation ; *Dinosaurs/anatomy & histology/physiology ; Extremities/anatomy & histology/physiology ; Feathers ; *Flight, Animal ; *Fossils ; Wings, Animal/anatomy & histology/physiology ; }, } @article {pmid23112330, year = {2012}, author = {Zelenitsky, DK and Therrien, F and Erickson, GM and DeBuhr, CL and Kobayashi, Y and Eberth, DA and Hadfield, F}, title = {Feathered non-avian dinosaurs from North America provide insight into wing origins.}, journal = {Science (New York, N.Y.)}, volume = {338}, number = {6106}, pages = {510-514}, doi = {10.1126/science.1225376}, pmid = {23112330}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology/*classification ; Feathers/*anatomy & histology ; North America ; Phylogeny ; Wings, Animal/*anatomy & histology ; }, abstract = {Previously described feathered dinosaurs reveal a fascinating record of feather evolution, although substantial phylogenetic gaps remain. Here we report the occurrence of feathers in ornithomimosaurs, a clade of non-maniraptoran theropods for which fossilized feathers were previously unknown. The Ornithomimus specimens, recovered from Upper Cretaceous deposits of Alberta, Canada, provide new insights into dinosaur plumage and the origin of the avian wing. Individuals from different growth stages reveal the presence of a filamentous feather covering throughout life and winglike structures on the forelimbs of adults. The appearance of winglike structures in older animals indicates that they may have evolved in association with reproductive behaviors. These specimens show that primordial wings originated earlier than previously thought, among non-maniraptoran theropods.}, } @article {pmid22962704, year = {2012}, author = {Smith, K}, title = {China's dinosaur hunter: The ground breaker.}, journal = {Nature}, volume = {489}, number = {7414}, pages = {22-25}, pmid = {22962704}, issn = {1476-4687}, mesh = {Animals ; Beak ; Birds/anatomy & histology/*classification ; China ; Dinosaurs/anatomy & histology/*classification/physiology ; Expeditions ; Feathers/anatomy & histology/physiology ; *Fossils ; History, 20th Century ; History, 21st Century ; Museums ; Paleontology/*history/standards ; Peer Review, Research/standards ; *Phylogeny ; }, } @article {pmid22954658, year = {2013}, author = {Knell, RJ and Naish, D and Tomkins, JL and Hone, DW}, title = {Sexual selection in prehistoric animals: detection and implications.}, journal = {Trends in ecology & evolution}, volume = {28}, number = {1}, pages = {38-47}, doi = {10.1016/j.tree.2012.07.015}, pmid = {22954658}, issn = {1872-8383}, mesh = {Animals ; *Biological Evolution ; Biometry ; Dinosaurs ; Feathers ; *Fossils ; Horns ; *Mating Preference, Animal ; *Selection, Genetic ; *Sex Characteristics ; Sexual Maturation ; }, abstract = {Many fossil animals bear traits such as crests or horns that probably functioned as sexually selected signals or weapons. Interpretations of these structures as functioning in mate choice or intrasexual contests are often controversial, with interpretations based on biomechanics or physiology being favoured by many. Although testing hypotheses based on sexual selection can be difficult, especially given that there is no single, reliable means of recognising sexual selection, we argue that it is not impossible; indeed, there are now several cases where sexual selection is strongly supported. In other cases, a careful study of features such as sexual dimorphism, ontogeny, and allometry, coupled with testing of alternative hypotheses, will be necessary to distinguish between possible explanations for exaggerated features.}, } @article {pmid22753486, year = {2012}, author = {Rauhut, OW and Foth, C and Tischlinger, H and Norell, MA}, title = {Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {109}, number = {29}, pages = {11746-11751}, pmid = {22753486}, issn = {1091-6490}, mesh = {Animals ; *Biological Evolution ; Bone and Bones/*anatomy & histology ; Dinosaurs/*anatomy & histology/classification ; Feathers/*anatomy & histology ; *Fossils ; Germany ; Integumentary System/*anatomy & histology ; Phylogeny ; Species Specificity ; }, abstract = {Recent discoveries in Asia have greatly increased our understanding of the evolution of dinosaurs' integumentary structures, revealing a previously unexpected diversity of "protofeathers" and feathers. However, all theropod dinosaurs with preserved feathers reported so far are coelurosaurs. Evidence for filaments or feathers in noncoelurosaurian theropods is circumstantial and debated. Here we report an exceptionally preserved skeleton of a juvenile megalosauroid, Sciurumimus albersdoerferi n. gen., n. sp., from the Late Jurassic of Germany, which preserves a filamentous plumage at the tail base and on parts of the body. These structures are identical to the type 1 feathers that have been reported in some ornithischians, the basal tyrannosaur Dilong, the basal therizinosauroid Beipiaosaurus, and, probably, in the basal coelurosaur Sinosauropteryx. Sciurumimus albersdoerferi represents the phylogenetically most basal theropod that preserves direct evidence for feathers and helps close the gap between feathers reported in coelurosaurian theropods and filaments in ornithischian dinosaurs, further supporting the homology of these structures. The specimen of Sciurumimus is the most complete megalosauroid yet discovered and helps clarify significant anatomical details of this important basal theropod clade, such as the complete absence of the fourth digit of the manus. The dentition of this probably early-posthatchling individual is markedly similar to that of basal coelurosaurian theropods, indicating that coelurosaur occurrences based on isolated teeth should be used with caution.}, } @article {pmid22524223, year = {2012}, author = {Bergmann, U and Manning, PL and Wogelius, RA}, title = {Chemical mapping of paleontological and archeological artifacts with synchrotron X-rays.}, journal = {Annual review of analytical chemistry (Palo Alto, Calif.)}, volume = {5}, number = {}, pages = {361-389}, doi = {10.1146/annurev-anchem-062011-143019}, pmid = {22524223}, issn = {1936-1335}, mesh = {Animals ; Archaeology/instrumentation/*methods ; Birds/metabolism ; Dinosaurs/metabolism ; Equipment Design ; *Fossils ; Paleontology/instrumentation/*methods ; Reptiles/metabolism ; Spectrometry, X-Ray Emission/instrumentation/*methods ; Synchrotrons/instrumentation ; }, abstract = {The application of the recently developed synchrotron rapid scanning X-ray fluorescence (SRS-XRF) technique to the mapping of large objects is the focus of this review. We discuss the advantages of SRS-XRF over traditional systems and the use of other synchrotron radiation (SR) techniques to provide corroborating spectroscopic and diffraction analyses during the same analytical session. After reviewing routine techniques used to analyze precious specimens, we present several case studies that show how SR-based methods have been successfully applied in archeology and paleontology. For example, SRS-XRF imaging of a seventh-century Qur'ān palimpsest and an overpainted original opera score from Luigi Cherubini is described. We also review the recent discovery of soft-tissue residue in fossils of Archaeopteryx and an ancient reptile, as well as work that has successfully resolved the remnants of pigment in Confuciusornis sanctus, a 120-million-year-old fossil of the oldest documented bird with a fully derived avian beak.}, } @article {pmid22481363, year = {2012}, author = {Xu, X and Wang, K and Zhang, K and Ma, Q and Xing, L and Sullivan, C and Hu, D and Cheng, S and Wang, S}, title = {A gigantic feathered dinosaur from the lower cretaceous of China.}, journal = {Nature}, volume = {484}, number = {7392}, pages = {92-95}, pmid = {22481363}, issn = {1476-4687}, mesh = {Animals ; Biological Evolution ; *Body Size ; China ; Dinosaurs/*anatomy & histology/classification ; *Feathers/anatomy & histology ; *Fossils ; Phylogeny ; Skeleton ; Skull/anatomy & histology ; }, abstract = {Numerous feathered dinosaur specimens have recently been recovered from the Middle-Upper Jurassic and Lower Cretaceous deposits of northeastern China, but most of them represent small animals. Here we report the discovery of a gigantic new basal tyrannosauroid, Yutyrannus huali gen. et sp. nov., based on three nearly complete skeletons representing two distinct ontogenetic stages from the Lower Cretaceous Yixian Formation of Liaoning Province, China. Y. huali shares some features, particularly of the cranium, with derived tyrannosauroids, but is similar to other basal tyrannosauroids in possessing a three-fingered manus and a typical theropod pes. Morphometric analysis suggests that Y. huali differed from tyrannosaurids in its growth strategy. Most significantly, Y. huali bears long filamentous feathers, thus providing direct evidence for the presence of extensively feathered gigantic dinosaurs and offering new insights into early feather evolution.}, } @article {pmid22445298, year = {2012}, author = {Gao, TP and Shih, CK and Xu, X and Wang, S and Ren, D}, title = {Mid-Mesozoic flea-like ectoparasites of feathered or haired vertebrates.}, journal = {Current biology : CB}, volume = {22}, number = {8}, pages = {732-735}, doi = {10.1016/j.cub.2012.03.012}, pmid = {22445298}, issn = {1879-0445}, mesh = {Animals ; Body Size ; China ; Dinosaurs/parasitology ; Feathers ; *Fossils ; *Host-Parasite Interactions ; Insecta/*anatomy & histology/*classification/physiology ; Siphonaptera ; Vertebrates/*parasitology ; }, abstract = {Parasite-host associations among insects and mammals or birds are well attended by neontological studies [1]. An Eocene bird louse compression fossil [2, 3] and several flea specimens from Eocene and Oligocene ambers [4-8], reported to date, are exceptionally similar to living louse and flea taxa. But the origin, morphology, and early evolution of parasites and their associations with hosts are poorly known [9, 10] due to sparse records of putative ectoparasites with uncertain classification in the Mesozoic, most lacking mouthpart information and other critical details of the head morphology [11-15]. Here we present two primitive flea-like species assigned to the Pseudopulicidae Gao, Shih et Ren familia nova (fam. nov.), Pseudopulex jurassicus Gao, Shih et Ren genus novum et species nova (gen. et sp. nov) from the Middle Jurassic [16] and P. magnus Gao, Shih et Ren sp. nov. from the Early Cretaceous in China [17]. They exhibit many features of ectoparasitic insects. Large body size and long serrated stylets for piercing tough and thick skin or hides of hosts suggest that these primitive ectoparasites might have lived on and sucked the blood of relatively large hosts, such as contemporaneous feathered dinosaurs and/or pterosaurs or medium-sized mammals (found in the Early Cretaceous, but not the Middle Jurassic).}, } @article {pmid22403389, year = {2012}, author = {Li, Q and Gao, KQ and Meng, Q and Clarke, JA and Shawkey, MD and D'Alba, L and Pei, R and Ellison, M and Norell, MA and Vinther, J}, title = {Reconstruction of Microraptor and the evolution of iridescent plumage.}, journal = {Science (New York, N.Y.)}, volume = {335}, number = {6073}, pages = {1215-1219}, doi = {10.1126/science.1213780}, pmid = {22403389}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; China ; Color ; Dinosaurs/*anatomy & histology ; Discriminant Analysis ; Feathers/anatomy & histology/*ultrastructure ; Keratins/analysis/chemistry ; Melanins/analysis/chemistry ; Melanosomes/*ultrastructure ; Phylogeny ; *Pigmentation ; }, abstract = {Iridescent feather colors involved in displays of many extant birds are produced by nanoscale arrays of melanin-containing organelles (melanosomes). Data relevant to the evolution of these colors and the properties of melanosomes involved in their generation have been limited. A data set sampling variables of extant avian melanosomes reveals that those forming most iridescent arrays are distinctly narrow. Quantitative comparison of these data with melanosome imprints densely sampled from a previously unknown specimen of the Early Cretaceous feathered Microraptor predicts that its plumage was predominantly iridescent. The capacity for simple iridescent arrays is thus minimally inferred in paravian dinosaurs. This finding and estimation of Microraptor feathering consistent with an ornamental function for the tail suggest a centrality for signaling in early evolution of plumage and feather color.}, } @article {pmid22388812, year = {2012}, author = {Huang, D and Engel, MS and Cai, C and Wu, H and Nel, A}, title = {Diverse transitional giant fleas from the Mesozoic era of China.}, journal = {Nature}, volume = {483}, number = {7388}, pages = {201-204}, pmid = {22388812}, issn = {1476-4687}, mesh = {Animals ; *Body Size ; China ; Dinosaurs/parasitology ; *Fossils ; History, Ancient ; Mammals/parasitology ; Parasites/anatomy & histology/classification ; *Phylogeny ; Siphonaptera/*anatomy & histology/*classification ; }, abstract = {Fleas are one of the major lineages of ectoparasitic insects and are now highly specialized for feeding on the blood of birds or mammals. This has isolated them among holometabolan insect orders, although they derive from the Antliophora (scorpionflies and true flies). Like most ectoparasitic lineages, their fossil record is meagre and confined to Cenozoic-era representatives of modern families, so that we lack evidence of the origins of fleas in the Mesozoic era. The origins of the first recognized Cretaceous stem-group flea, Tarwinia, remains highly controversial. Here we report fossils of the oldest definitive fleas--giant forms from the Middle Jurassic and Early Cretaceous periods of China. They exhibit many defining features of fleas but retain primitive traits such as non-jumping hindlegs. More importantly, all have stout and elongate sucking siphons for piercing the hides of their hosts, implying that these fleas may be rooted among the pollinating 'long siphonate' scorpionflies of the Mesozoic. Their special morphology suggests that their earliest hosts were hairy or feathered 'reptilians', and that they radiated to mammalian and bird hosts later in the Cenozoic.}, } @article {pmid22344430, year = {2012}, author = {Dove, CJ and Straker, LC}, title = {Comment on "A diverse assemblage of Late Cretaceous dinosaur and bird feathers from Canadian amber".}, journal = {Science (New York, N.Y.)}, volume = {335}, number = {6070}, pages = {796; author reply 796}, doi = {10.1126/science.1216484}, pmid = {22344430}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; *Fossils ; *Pigmentation ; }, abstract = {McKellar et al. (Reports, 16 September 2011, p. 1619) analyzed Late Cretaceous amber specimens from Canada and identified some filaments as dinosaurian protofeathers. We argue that their analysis and data do not provide sufficient evidence to conclude that such filaments are feather-like structures. Further investigation, including destructive sampling, must be carried out for more convincing conclusions.}, } @article {pmid22304966, year = {2012}, author = {Heers, AM and Dial, KP}, title = {From extant to extinct: locomotor ontogeny and the evolution of avian flight.}, journal = {Trends in ecology & evolution}, volume = {27}, number = {5}, pages = {296-305}, doi = {10.1016/j.tree.2011.12.003}, pmid = {22304966}, issn = {1872-8383}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/*growth & development/physiology ; Dinosaurs/anatomy & histology/*growth & development/physiology ; Feathers/anatomy & histology ; *Flight, Animal ; Fossils ; *Locomotion ; }, abstract = {Evolutionary transformations are recorded by fossils with transitional morphologies, and are key to understanding the history of life. Reconstructing these transformations requires interpreting functional attributes of extinct forms by exploring how similar features function in extant organisms. However, extinct-extant comparisons are often difficult, because extant adult forms frequently differ substantially from fossil material. Here, we illustrate how postnatal developmental transitions in extant birds can provide rich and novel insights into evolutionary transformations in theropod dinosaurs. Although juveniles have not been a focus of extinct-extant comparisons, developing juveniles in many groups transition through intermediate morphological, functional and behavioral stages that anatomically and conceptually parallel evolutionary transformations. Exploring developmental transitions may thus disclose observable, ecologically relevant answers to long puzzling evolutionary questions.}, } @article {pmid22273675, year = {2012}, author = {Carney, RM and Vinther, J and Shawkey, MD and D'Alba, L and Ackermann, J}, title = {New evidence on the colour and nature of the isolated Archaeopteryx feather.}, journal = {Nature communications}, volume = {3}, number = {}, pages = {637}, pmid = {22273675}, issn = {2041-1723}, mesh = {Animals ; Biological Evolution ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology/ultrastructure ; Flight, Animal ; Fossils ; Melanosomes/physiology ; Microscopy, Electron, Scanning/methods ; Models, Statistical ; Phylogeny ; Probability ; Wings, Animal/anatomy & histology ; }, abstract = {Archaeopteryx has been regarded as an icon of evolution ever since its discovery from the Late Jurassic limestone deposits of Solnhofen, Germany in 1861. Here we report the first evidence of colour from Archaeopteryx based on fossilized colour-imparting melanosomes discovered in this isolated feather specimen. Using a phylogenetically diverse database of extant bird feathers, statistical analysis of melanosome morphology predicts that the original colour of this Archaeopteryx feather was black, with 95% probability. Furthermore, reexamination of the feather's morphology leads us to interpret it as an upper major primary covert, contrary to previous interpretations. Additional findings reveal that the specimen is preserved as an organosulphur residue, and that barbule microstructure identical to that of modern bird feathers had evolved as early as the Jurassic. As in extant birds, the extensive melanization would have provided structural advantages to the Archaeopteryx wing feather during this early evolutionary stage of dinosaur flight.}, } @article {pmid21949721, year = {2011}, author = {Zanno, LE and Varricchio, DJ and O'Connor, PM and Titus, AL and Knell, MJ}, title = {A new troodontid theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America.}, journal = {PloS one}, volume = {6}, number = {9}, pages = {e24487}, pmid = {21949721}, issn = {1932-6203}, mesh = {Animals ; Bone and Bones/diagnostic imaging ; Dinosaurs/anatomy & histology/*classification ; North America ; *Paleontology ; Phylogeny ; X-Ray Microtomography ; }, abstract = {BACKGROUND: Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species--Troodon formosus--presently known from substantial skeletal remains.

Here we report a gracile new troodontid theropod--Talos sampsoni gen. et sp. nov.--from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar. MicroCT scans reveal extreme pathological remodeling on pedal phalanx II-1 of the holotype specimen likely resulting from physical trauma and subsequent infectious processes.

CONCLUSION/SIGNIFICANCE: Talos sampsoni adds to the singularity of the Kaiparowits Formation dinosaur fauna, which is represented by at least 10 previously unrecognized species including the recently named ceratopsids Utahceratops and Kosmoceratops, the hadrosaurine Gryposaurus monumentensis, the tyrannosaurid Teratophoneus, and the oviraptorosaurian Hagryphus. The presence of a distinct troodontid taxon in the Kaiparowits Formation supports the hypothesis that late Campanian dinosaurs of the Western Interior Basin exhibited restricted geographic ranges and suggests that the taxonomic diversity of Late Cretaceous troodontids from North America is currently underestimated. An apparent traumatic injury to the foot of Talos with evidence of subsequent healing sheds new light on the paleobiology of deinonychosaurians by bolstering functional interpretations of prey grappling and/or intraspecific combat for the second pedal digit, and supporting trackway evidence indicating a minimal role in weight bearing.}, } @article {pmid21937667, year = {2011}, author = {Koehl, MA and Evangelista, D and Yang, K}, title = {Using physical models to study the gliding performance of extinct animals.}, journal = {Integrative and comparative biology}, volume = {51}, number = {6}, pages = {1002-1018}, doi = {10.1093/icb/icr112}, pmid = {21937667}, issn = {1557-7023}, mesh = {Animals ; Biological Evolution ; Biomechanical Phenomena ; Body Size ; Dinosaurs/*physiology ; *Extinction, Biological ; *Flight, Animal ; Fossils ; Models, Animal ; Orientation ; Posture ; Wind ; }, abstract = {Aerodynamic studies using physical models of fossil organisms can provide quantitative information about how performance of defined activities, such as gliding, depends on specific morphological features. Such analyses allow us to rule out hypotheses about the function of extinct organisms that are not physically plausible and to determine if and how specific morphological features and postures affect performance. The purpose of this article is to provide a practical guide for the design of dynamically scaled physical models to study the gliding of extinct animals using examples from our research on the theropod dinosaur, †Microraptor gui, which had flight feathers on its hind limbs as well as on its forelimbs. Analysis of the aerodynamics of †M. gui can shed light on the design of gliders with large surfaces posterior to the center of mass and provide functional information to evolutionary biologists trying to unravel the origins of flight in the dinosaurian ancestors and sister groups to birds. Measurements of lift, drag, side force, and moments in pitch, roll, and yaw on models in a wind tunnel can be used to calculate indices of gliding and parachuting performance, aerodynamic static stability, and control effectiveness in maneuvering. These indices permit the aerodynamic performance of bodies of different shape, size, stiffness, texture, and posture to be compared and thus can provide insights about the design of gliders, both biological and man-made. Our measurements of maximum lift-to-drag ratios of 2.5-3.1 for physical models of †M. gui suggest that its gliding performance was similar to that of flying squirrels and that the various leg postures that might have been used by †M. gui make little difference to that aspect of aerodynamic performance. We found that body orientation relative to the movement of air past the animal determines whether it is difficult or easy to maneuver.}, } @article {pmid21921196, year = {2011}, author = {McKellar, RC and Chatterton, BD and Wolfe, AP and Currie, PJ}, title = {A diverse assemblage of Late Cretaceous dinosaur and bird feathers from Canadian amber.}, journal = {Science (New York, N.Y.)}, volume = {333}, number = {6049}, pages = {1619-1622}, doi = {10.1126/science.1203344}, pmid = {21921196}, issn = {1095-9203}, mesh = {Amber ; Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Canada ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; *Fossils ; *Pigmentation ; }, abstract = {The fossil record of early feathers has relied on carbonized compressions that lack fine structural detail. Specimens in amber are preserved in greater detail, but they are rare. Late Cretaceous coal-rich strata from western Canada provide the richest and most diverse Mesozoic feather assemblage yet reported from amber. The fossils include primitive structures closely matching the protofeathers of nonavian dinosaurs, offering new insights into their structure and function. Additional derived morphologies confirm that plumage specialized for flight and underwater diving had evolved in Late Cretaceous birds. Because amber preserves feather structure and pigmentation in unmatched detail, these fossils provide novel insights regarding feather evolution.}, } @article {pmid21921190, year = {2011}, author = {Norell, MA}, title = {Paleontology. Fossilized feathers.}, journal = {Science (New York, N.Y.)}, volume = {333}, number = {6049}, pages = {1590-1591}, doi = {10.1126/science.1212049}, pmid = {21921190}, issn = {1095-9203}, mesh = {Amber ; Animals ; Biological Evolution ; *Birds/anatomy & histology ; *Dinosaurs/anatomy & histology ; Extinction, Biological ; *Feathers/anatomy & histology/ultrastructure ; *Fossils ; Melanosomes/ultrastructure ; *Pigmentation ; Trace Elements ; }, } @article {pmid21898788, year = {2011}, author = {Greenwold, MJ and Sawyer, RH}, title = {Linking the molecular evolution of avian beta (β) keratins to the evolution of feathers.}, journal = {Journal of experimental zoology. Part B, Molecular and developmental evolution}, volume = {316}, number = {8}, pages = {609-616}, doi = {10.1002/jez.b.21436}, pmid = {21898788}, issn = {1552-5015}, mesh = {Animals ; Bayes Theorem ; Birds ; *Evolution, Molecular ; Feathers/growth & development/*metabolism ; Fossils ; Protein Structure, Tertiary/genetics/physiology ; beta-Keratins/*genetics/*metabolism ; }, abstract = {Feathers of today's birds are constructed of beta (β)-keratins, structural proteins of the epidermis that are found solely in reptiles and birds. Discoveries of "feathered dinosaurs" continue to stimulate interest in the evolutionary origin of feathers, but few studies have attempted to link the molecular evolution of their major structural proteins (β-keratins) to the appearance of feathers in the fossil record. Using molecular dating methods, we show that before the appearance of Anchiornis (∼155 Million years ago (Ma)) the basal β-keratins of birds began diverging from their archosaurian ancestor ∼216 Ma. However, the subfamily of feather β-keratins, as found in living birds, did not begin diverging until ∼143 Ma. Thus, the pennaceous feathers on Anchiornis, while being constructed of avian β-keratins, most likely did not contain the feather β-keratins found in the feathers of modern birds. Our results demonstrate that the evolutionary origin of feathers does not coincide with the molecular evolution of the feather β-keratins found in modern birds. More likely, during the Late Jurassic, the epidermal structures that appeared on organisms in the lineage leading to birds, including early forms of feathers, were constructed of avian β-keratins other than those found in the feathers of modern birds. Recent biophysical studies of the β-keratins in feathers support the view that the appearance of the subfamily of feather β-keratins altered the biophysical nature of the feather establishing its role in powered flight.}, } @article {pmid21857918, year = {2011}, author = {Dececchi, TA and Larsson, HC}, title = {Assessing arboreal adaptations of bird antecedents: testing the ecological setting of the origin of the avian flight stroke.}, journal = {PloS one}, volume = {6}, number = {8}, pages = {e22292}, pmid = {21857918}, issn = {1932-6203}, mesh = {Adaptation, Physiological/*physiology ; Animals ; Biological Evolution ; Birds/classification/genetics/*physiology ; Cluster Analysis ; Dinosaurs/physiology ; Ecology ; Ecosystem ; Flight, Animal/*physiology ; Forelimb/anatomy & histology ; Fossils ; Hindlimb/anatomy & histology ; Locomotion/physiology ; Mammals/physiology ; *Phylogeny ; Reptiles/physiology ; Species Specificity ; Trees ; }, abstract = {The origin of avian flight is a classic macroevolutionary transition with research spanning over a century. Two competing models explaining this locomotory transition have been discussed for decades: ground up versus trees down. Although it is impossible to directly test either of these theories, it is possible to test one of the requirements for the trees-down model, that of an arboreal paravian. We test for arboreality in non-avian theropods and early birds with comparisons to extant avian, mammalian, and reptilian scansors and climbers using a comprehensive set of morphological characters. Non-avian theropods, including the small, feathered deinonychosaurs, and Archaeopteryx, consistently and significantly cluster with fully terrestrial extant mammals and ground-based birds, such as ratites. Basal birds, more advanced than Archaeopteryx, cluster with extant perching ground-foraging birds. Evolutionary trends immediately prior to the origin of birds indicate skeletal adaptations opposite that expected for arboreal climbers. Results reject an arboreal capacity for the avian stem lineage, thus lending no support for the trees-down model. Support for a fully terrestrial ecology and origin of the avian flight stroke has broad implications for the origin of powered flight for this clade. A terrestrial origin for the avian flight stroke challenges the need for an intermediate gliding phase, presents the best resolved series of the evolution of vertebrate powered flight, and may differ fundamentally from the origin of bat and pterosaur flight, whose antecedents have been postulated to have been arboreal and gliding.}, } @article {pmid21719643, year = {2011}, author = {Wogelius, RA and Manning, PL and Barden, HE and Edwards, NP and Webb, SM and Sellers, WI and Taylor, KG and Larson, PL and Dodson, P and You, H and Da-qing, L and Bergmann, U}, title = {Trace metals as biomarkers for eumelanin pigment in the fossil record.}, journal = {Science (New York, N.Y.)}, volume = {333}, number = {6049}, pages = {1622-1626}, doi = {10.1126/science.1205748}, pmid = {21719643}, issn = {1095-9203}, mesh = {Animals ; Biomarkers/analysis ; *Birds ; Calcium/analysis ; Copper/*analysis ; Dinosaurs ; Extinction, Biological ; *Feathers/ultrastructure ; *Fossils ; Melanins/*analysis ; Melanosomes/*chemistry ; Microscopy, Electron, Scanning ; Organometallic Compounds/*analysis ; *Pigmentation ; Trace Elements/*analysis ; X-Ray Absorption Spectroscopy ; Zinc/analysis ; }, abstract = {Well-preserved fossils of pivotal early bird and nonavian theropod species have provided unequivocal evidence for feathers and/or downlike integuments. Recent studies have reconstructed color on the basis of melanosome structure; however, the chemistry of these proposed melanosomes has remained unknown. We applied synchrotron x-ray techniques to several fossil and extant organisms, including Confuciusornis sanctus, in order to map and characterize possible chemical residues of melanin pigments. Results show that trace metals, such as copper, are present in fossils as organometallic compounds most likely derived from original eumelanin. The distribution of these compounds provides a long-lived biomarker of melanin presence and density within a range of fossilized organisms. Metal zoning patterns may be preserved long after melanosome structures have been destroyed.}, } @article {pmid21437381, year = {2011}, author = {Sayão, JM and Saraiva, AA and Uejima, AM}, title = {New evidence of feathers in the Crato Formation supporting a reappraisal on the presence of Aves.}, journal = {Anais da Academia Brasileira de Ciencias}, volume = {83}, number = {1}, pages = {197-210}, doi = {10.1590/s0001-37652011000100010}, pmid = {21437381}, issn = {1678-2690}, mesh = {Animals ; *Biological Evolution ; *Birds ; Brazil ; *Dinosaurs ; *Feathers ; *Fossils ; Paleontology ; }, abstract = {The preservation of delicate structures such as feathers is very rare in the paleontological record, due to the fragility of their components. Fossil feathers have been reported from approximately 50 deposits around the world, from the Late Jurassic to the Pleistocene. In Brazil initial findings consisted of a primary feather of a large bird found in the Tremembé Formation. Other occurrences are preserved in the Crato Formation, where several symmetrical and one single asymmetrical feather was found. Based on three new specimens and reassessing further feather occurrences we cannot confirm the presence of volant Aves in this deposit. The presence of an asymmetrical feather without barbules and hooks hints at the previous existence of a flightless animal within this deposit, possibly a flightlessness bird or a non-avian theropod. Conversely, the presence of a feather from morphotype II present in Tyrannosauroidea, Compsognathidae, Therizinosauroidea and Dromeosauridae, points to a non-theropod origin. Since there are no confirmed records of birds and other feathered archosaurs in the region to date, more evidence is required to identify the animal from which these structures originated.}, } @article {pmid21048715, year = {2010}, author = {Prum, RO}, title = {Moulting tail feathers in a juvenile oviraptorisaur.}, journal = {Nature}, volume = {468}, number = {7320}, pages = {E1; discussion E2}, pmid = {21048715}, issn = {1476-4687}, mesh = {Aging ; Animals ; Biological Evolution ; China ; Dinosaurs/*anatomy & histology/growth & development ; Feathers/*anatomy & histology/*growth & development ; *Fossils ; Models, Biological ; *Molting ; Strigiformes/anatomy & histology/growth & development ; Tail/*anatomy & histology ; }, abstract = {Xu et al. describe the extraordinarily preserved feathers from two subadults of the oviraptorisaur Similicaudipteryx from the Yixian Formation of Liaoning, China. The preserved tail feathers of the juvenile specimen (STM4.1) show a morphology not previously observed in any fossil feathers. The tail feathers of an older, immature specimen (STM22-6) show a typical closed pennaceous structure with a prominent, planar vane. I propose that the feathers of the tail of the juvenile specimen are not a specialized feather generation, but fossilized 'pin feathers' or developing feather germs.}, } @article {pmid20829793, year = {2010}, author = {Ortega, F and Escaso, F and Sanz, JL}, title = {A bizarre, humped Carcharodontosauria (Theropoda) from the lower cretaceous of Spain.}, journal = {Nature}, volume = {467}, number = {7312}, pages = {203-206}, pmid = {20829793}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology/*classification ; *Fossils ; Spain ; }, abstract = {Carcharodontosaurs were the largest predatory dinosaurs, and their early evolutionary history seems to be more intricate than was previously thought. Until recently, carcharodontosaurs were restricted to a group of large theropods inhabiting the Late Cretaceous Gondwanan land masses, but in the last few years Laurasian evidence has been causing a reevaluation of their initial diversification. Here we describe an almost complete and exquisitely preserved skeleton of a medium-sized (roughly six metres long) theropod from the Lower Cretaceous series (Barremian stage) Konservat-Lagerstätte of Las Hoyas in Cuenca, Spain. Cladistic analysis supports the idea that the new taxon Concavenator corcovatus is a primitive member of Carcharodontosauria, exhibiting two unusual features: elongation of the neurapophyses of two presacral vertebrae forming a pointed, hump-like structure and a series of small bumps on the ulna. We think that these bumps are homologous to quill knobs present on some modern birds; the knobs are related to the insertion area of follicular ligaments that anchor the roots of the flight feathers (remiges) to the arm. We propose that Concavenator has integumentary follicular structures inserted on the ulna, as in modern birds. Because scales do not have follicles, we consider the structures anchored to the Concavenator arms to be non-scale skin appendages homologous to the feathers of modern birds. If this is true, then the phylogenetic bracket for the presence of non-scale skin structures homologous to feathers in theropod dinosaurs would be extended to the Neotetanurae, enlarging the scope for explaining the origin of feathers in theropods.}, } @article {pmid20457935, year = {2010}, author = {Bergmann, U and Morton, RW and Manning, PL and Sellers, WI and Farrar, S and Huntley, KG and Wogelius, RA and Larson, P}, title = {Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {107}, number = {20}, pages = {9060-9065}, pmid = {20457935}, issn = {1091-6490}, mesh = {Animals ; Birds/*anatomy & histology ; Bone and Bones/anatomy & histology/*chemistry ; Feathers/anatomy & histology/*chemistry ; *Fossils ; Metals, Heavy/analysis ; Phosphorus/analysis ; Spectrometry, X-Ray Emission/*methods ; Sulfur/analysis ; Synchrotrons ; }, abstract = {Evolution of flight in maniraptoran dinosaurs is marked by the acquisition of distinct avian characters, such as feathers, as seen in Archaeopteryx from the Solnhofen limestone. These rare fossils were pivotal in confirming the dinosauria-avian lineage. One of the key derived avian characters is the possession of feathers, details of which were remarkably preserved in the Lagerstätte environment. These structures were previously simply assumed to be impressions; however, a detailed chemical analysis has, until now, never been completed on any Archaeopteryx specimen. Here we present chemical imaging via synchrotron rapid scanning X-ray fluorescence (SRS-XRF) of the Thermopolis Archaeopteryx, which shows that portions of the feathers are not impressions but are in fact remnant body fossil structures, maintaining elemental compositions that are completely different from the embedding geological matrix. Our results indicate phosphorous and sulfur retention in soft tissue as well as trace metal (Zn and Cu) retention in bone. Other previously unknown chemical details of Archaeopteryx are also revealed in this study including: bone chemistry, taphonomy (fossilization process), and curation artifacts. SRS-XRF represents a major advancement in the study of the life chemistry and fossilization processes of Archaeopteryx and other extinct organisms because it is now practical to image the chemistry of large specimens rapidly at concentration levels of parts per million. This technique has wider application to the archaeological, forensic, and biological sciences, enabling the mapping of "unseen" compounds critical to understanding biological structures, modes of preservation, and environmental context.}, } @article {pmid20428169, year = {2010}, author = {Xu, X and Zheng, X and You, H}, title = {Exceptional dinosaur fossils show ontogenetic development of early feathers.}, journal = {Nature}, volume = {464}, number = {7293}, pages = {1338-1341}, pmid = {20428169}, issn = {1476-4687}, mesh = {Animals ; Birds/anatomy & histology/classification ; China ; Dinosaurs/*anatomy & histology/classification/*growth & development ; Feathers/*anatomy & histology/*growth & development ; *Fossils ; Phylogeny ; }, abstract = {Recent discoveries of feathered dinosaur specimens have greatly improved our understanding of the origin and early evolution of feathers, but little information is available on the ontogenetic development of early feathers. Here we describe an early-juvenile specimen and a late-juvenile specimen, both referable to the oviraptorosaur Similicaudipteryx, recovered from the Lower Cretaceous Yixian Formation of western Liaoning, China. The two specimens have strikingly different remiges and rectrices, suggesting that a radical morphological change occurred during feather development, as is the case for modern feathers. However, both the remiges and the rectrices are proximally ribbon-like in the younger specimen but fully pennaceous in the older specimen, a pattern not known in any modern bird. In combination with the wide distribution of proximally ribbon-like pennaceous feathers and elongate broad filamentous feathers among extinct theropods, this find suggests that early feathers were developmentally more diverse than modern ones and that some developmental features, and the resultant morphotypes, have been lost in feather evolution.}, } @article {pmid20354675, year = {2010}, author = {Lingham-Soliar, T and Plodowski, G}, title = {The integument of Psittacosaurus from Liaoning Province, China: taphonomy, epidermal patterns and color of a ceratopsian dinosaur.}, journal = {Die Naturwissenschaften}, volume = {97}, number = {5}, pages = {479-486}, pmid = {20354675}, issn = {1432-1904}, mesh = {Animal Feed ; Animals ; China ; Dinosaurs/*anatomy & histology/physiology ; Epidermis/*anatomy & histology ; *Fossils ; Paleontology ; Pharynx/anatomy & histology ; Plants ; Skin Pigmentation/*physiology ; }, abstract = {Preserved skin of small dinosaurs is rare. Here, a specimen of the ceratopsian dinosaur, Psittacosaurus, presents some of the best preserved epidermal scales observed to date in a relatively small dinosaur, over wide areas extending from the head to the tail. We study the preserved epidermis of SMF R 4970, the different types of scales, color, and patterns, and their respective locations in the body. We use modern application of high-power digital imaging for close-up analysis of the tubercles and fragments of preserved color. Three types of scales are preserved, large plate-like scales, smaller polygonal scales or tubercles, and round pebble-like scales. The sizes of the plate-like scales vary in different parts of the body and vanish altogether posteriorly. Light and dark cryptic patterns are created by the associations of the tubercle and plate-like scales, and there is also evidence of countershading in the proximal caudal region, the body darker dorsally and lighter ventrally. Perhaps most impressive are the distinctive pigmented impressions of scales over most of the skeletal elements. The pigmentation follows the curvature of the bones implying that when it was deposited, the skin was still pliable and able to wrap around the visible parts of the elements. The present record of color is the first in a non-theropod dinosaur and only the second record in a non-avian dinosaur. Because of its resistance to degradation and ability to produce various color tones from yellows to blacks, we suggest that melanin was the dominant chemical involved in the coloration of Psittacosaurus. The data here enable us to reconstruct the colors of Psittacosaurus as predominantly black and amber/brown, in cryptic patterns, somewhat dull, but useful to a prey animal. Indeed, skin pigment within a partially degraded bone indicates that Psittacosaurus was scavenged shortly after death. The theropod dinosaur Sinosauropteryx has recently been reported to have naturally pigmented integumental structures, which the authors interpret as proof that they are protofeathers and not support fibers of collagen. Our findings in Psittacosaurus, on the other hand, indicate a more parsimonious and less profound alternative explanation, i.e., decomposition of the skin releases pigments that readily permeate underlying structures.}, } @article {pmid20236961, year = {2010}, author = {Chiappe, LM and Marugán-Lobón, J and Chinsamy, A}, title = {Palaeobiology of the Cretaceous bird Confuciusornis: a comment on Peters & Peters (2009).}, journal = {Biology letters}, volume = {6}, number = {4}, pages = {529-30; discussion 531-2}, pmid = {20236961}, issn = {1744-957X}, mesh = {Animals ; Birds/*anatomy & histology/physiology ; Body Size/physiology ; China ; Feathers/*anatomy & histology ; Female ; *Fossils ; Hindlimb/*anatomy & histology ; Male ; Sex Characteristics ; Tail/*anatomy & histology ; }, } @article {pmid20200032, year = {2010}, author = {Sullivan, C and Hone, DW and Xu, X and Zhang, F}, title = {The asymmetry of the carpal joint and the evolution of wing folding in maniraptoran theropod dinosaurs.}, journal = {Proceedings. Biological sciences}, volume = {277}, number = {1690}, pages = {2027-2033}, pmid = {20200032}, issn = {1471-2954}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology/classification ; Carpus, Animal/*physiology ; Dinosaurs/*anatomy & histology/classification ; Feathers ; Fossils ; Wings, Animal/*physiology ; }, abstract = {In extant birds, the hand is permanently abducted towards the ulna, and the wrist joint can bend extensively in this direction to fold the wing when not in use. Anatomically, this asymmetric mobility of the wrist results from the wedge-like shape of one carpal bone, the radiale, and from the well-developed convexity of the trochlea at the proximal end of the carpometacarpus. Among the theropod precursors of birds, a strongly convex trochlea is characteristic of Coelurosauria, a clade including the highly derived Maniraptora in addition to tyrannosaurs and compsognathids. The shape of the radiale can be quantified using a 'radiale angle' between the proximal and distal articular surfaces. Measurement of the radiale angle and reconstruction of ancestral states using squared-change parsimony shows that the angle was small (15 degrees) in primitive coelurosaurs but considerably larger (25 degrees) in primitive maniraptorans, indicating that the radiale was more wedge-shaped and the carpal joint more asymmetric. The radiale angle progressively increased still further within Maniraptora, with concurrent elongation of the forelimb feathers and the forelimb itself. Carpal asymmetry would have permitted avian-like folding of the forelimb in order to protect the plumage, an early advantage of the flexible, asymmetric wrist inherited by birds.}, } @article {pmid20169153, year = {2010}, author = {Hone, DW and Tischlinger, H and Xu, X and Zhang, F}, title = {The extent of the preserved feathers on the four-winged dinosaur Microraptor gui under ultraviolet light.}, journal = {PloS one}, volume = {5}, number = {2}, pages = {e9223}, pmid = {20169153}, issn = {1932-6203}, mesh = {Animals ; Biological Evolution ; Birds/anatomy & histology/classification ; China ; Dinosaurs/*anatomy & histology/classification ; Feathers/*anatomy & histology ; Flight, Animal ; Forelimb/anatomy & histology ; *Fossils ; Hindlimb/anatomy & histology ; Paleontology ; Sternum/anatomy & histology ; Technology, Radiologic/methods ; Ultraviolet Rays ; Wings, Animal/*anatomy & histology ; }, abstract = {BACKGROUND: The holotype of the theropod non-avian dinosaur Microraptor gui from the Early Cretaceous of China shows extensive preservation of feathers in a halo around the body and with flight feathers associated with both the fore and hindlimbs. It has been questioned as to whether or not the feathers did extend into the halo to reach the body, or had disassociated and moved before preservation. This taxon has important implications for the origin of flight in birds and the possibility of a four-winged gliding phase.

Examination of the specimen under ultraviolet light reveals that these feathers actually reach the body of the animal and were not disassociated from the bones. Instead they may have been chemically altered by the body tissues of the animal meaning that they did not carbonise close into the animal or more likely were covered by other decaying tissue, though evidence of their presence remains.

CONCLUSIONS/SIGNIFICANCE: These UV images show that the feathers preserved on the slab are genuinely associated with the skeleton and that their arrangement and orientation is likely correct. The methods used here to reveal hidden features of the specimen may be applicable to other specimens from the fossil beds of Liaoning that produced Microraptor.}, } @article {pmid20133792, year = {2010}, author = {Alexander, DE and Gong, E and Martin, LD and Burnham, DA and Falk, AR}, title = {Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {107}, number = {7}, pages = {2972-2976}, pmid = {20133792}, issn = {1091-6490}, mesh = {Animals ; Biomechanical Phenomena ; Dinosaurs/*physiology ; Flight, Animal/*physiology ; *Fossils ; *Models, Anatomic ; Wings, Animal/*physiology ; }, abstract = {Fossils of the remarkable dromaeosaurid Microraptor gui and relatives clearly show well-developed flight feathers on the hind limbs as well as the front limbs. No modern vertebrate has hind limbs functioning as independent, fully developed wings; so, lacking a living example, little agreement exists on the functional morphology or likely flight configuration of the hindwing. Using a detailed reconstruction based on the actual skeleton of one individual, cast in the round, we developed light-weight, three-dimensional physical models and performed glide tests with anatomically reasonable hindwing configurations. Models were tested with hindwings abducted and extended laterally, as well as with a previously described biplane configuration. Although the hip joint requires the hindwing to have at least 20 degrees of negative dihedral (anhedral), all configurations were quite stable gliders. Glide angles ranged from 3 degrees to 21 degrees with a mean estimated equilibrium angle of 13.7 degrees, giving a lift to drag ratio of 4.1:1 and a lift coefficient of 0.64. The abducted hindwing model's equilibrium glide speed corresponds to a glide speed in the living animal of 10.6 m x s(-1). Although the biplane model glided almost as well as the other models, it was structurally deficient and required an unlikely weight distribution (very heavy head) for stable gliding. Our model with laterally abducted hindwings represents a biologically and aerodynamically reasonable configuration for this four-winged gliding animal. M. gui's feathered hindwings, although effective for gliding, would have seriously hampered terrestrial locomotion.}, } @article {pmid20133521, year = {2010}, author = {Li, Q and Gao, KQ and Vinther, J and Shawkey, MD and Clarke, JA and D'Alba, L and Meng, Q and Briggs, DE and Prum, RO}, title = {Plumage color patterns of an extinct dinosaur.}, journal = {Science (New York, N.Y.)}, volume = {327}, number = {5971}, pages = {1369-1372}, doi = {10.1126/science.1186290}, pmid = {20133521}, issn = {1095-9203}, mesh = {Animal Communication ; Animals ; Behavior, Animal ; Birds/anatomy & histology ; Dinosaurs/*anatomy & histology ; Discriminant Analysis ; Feathers/*anatomy & histology/ultrastructure ; *Fossils ; Melanosomes/ultrastructure ; Phylogeny ; *Pigmentation ; }, abstract = {For as long as dinosaurs have been known to exist, there has been speculation about their appearance. Fossil feathers can preserve the morphology of color-imparting melanosomes, which allow color patterns in feathered dinosaurs to be reconstructed. Here, we have mapped feather color patterns in a Late Jurassic basal paravian theropod dinosaur. Quantitative comparisons with melanosome shape and density in extant feathers indicate that the body was gray and dark and the face had rufous speckles. The crown was rufous, and the long limb feathers were white with distal black spangles. The evolution of melanin-based within-feather pigmentation patterns may coincide with that of elongate pennaceous feathers in the common ancestor of Maniraptora, before active powered flight. Feathers may thus have played a role in sexual selection or other communication.}, } @article {pmid20110471, year = {2010}, author = {Stone, R}, title = {Paleontology. Bird-dinosaur link firmed up, and in brilliant Technicolor.}, journal = {Science (New York, N.Y.)}, volume = {327}, number = {5965}, pages = {508}, doi = {10.1126/science.327.5965.508}, pmid = {20110471}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; *Birds/anatomy & histology/classification/physiology ; Bone and Bones/anatomy & histology ; China ; *Dinosaurs/anatomy & histology/classification/physiology ; *Feathers/anatomy & histology/physiology ; Flight, Animal ; *Fossils ; Melanins/analysis ; Melanosomes/chemistry ; Pigmentation ; }, } @article {pmid20107440, year = {2010}, author = {Zhang, F and Kearns, SL and Orr, PJ and Benton, MJ and Zhou, Z and Johnson, D and Xu, X and Wang, X}, title = {Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds.}, journal = {Nature}, volume = {463}, number = {7284}, pages = {1075-1078}, pmid = {20107440}, issn = {1476-4687}, mesh = {Animals ; Birds/*anatomy & histology/classification ; China ; *Color ; Dinosaurs/*anatomy & histology/classification ; Extinction, Biological ; Feathers/anatomy & histology/*cytology/ultrastructure ; *Fossils ; Integumentary System/anatomy & histology ; *Melanosomes/physiology/ultrastructure ; Phylogeny ; *Pigmentation/physiology ; }, abstract = {Spectacular fossils from the Early Cretaceous Jehol Group of northeastern China have greatly expanded our knowledge of the diversity and palaeobiology of dinosaurs and early birds, and contributed to our understanding of the origin of birds, of flight, and of feathers. Pennaceous (vaned) feathers and integumentary filaments are preserved in birds and non-avian theropod dinosaurs, but little is known of their microstructure. Here we report that melanosomes (colour-bearing organelles) are not only preserved in the pennaceous feathers of early birds, but also in an identical manner in integumentary filaments of non-avian dinosaurs, thus refuting recent claims that the filaments are partially decayed dermal collagen fibres. Examples of both eumelanosomes and phaeomelanosomes have been identified, and they are often preserved in life position within the structure of partially degraded feathers and filaments. Furthermore, the data here provide empirical evidence for reconstructing the colours and colour patterning of these extinct birds and theropod dinosaurs: for example, the dark-coloured stripes on the tail of the theropod dinosaur Sinosauropteryx can reasonably be inferred to have exhibited chestnut to reddish-brown tones.}, } @article {pmid19816582, year = {2009}, author = {Erickson, GM and Rauhut, OW and Zhou, Z and Turner, AH and Inouye, BD and Hu, D and Norell, MA}, title = {Was dinosaurian physiology inherited by birds? Reconciling slow growth in archaeopteryx.}, journal = {PloS one}, volume = {4}, number = {10}, pages = {e7390}, pmid = {19816582}, issn = {1932-6203}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/growth & development/*physiology ; Bone and Bones/*anatomy & histology ; Dinosaurs/anatomy & histology/growth & development/*physiology ; Feathers/anatomy & histology/growth & development ; Flight, Animal/physiology ; Fossils ; Models, Anatomic ; Models, Biological ; Paleontology/methods ; Phylogeny ; }, abstract = {BACKGROUND: Archaeopteryx is the oldest and most primitive known bird (Avialae). It is believed that the growth and energetic physiology of basalmost birds such as Archaeopteryx were inherited in their entirety from non-avialan dinosaurs. This hypothesis predicts that the long bones in these birds formed using rapidly growing, well-vascularized woven tissue typical of non-avialan dinosaurs.

We report that Archaeopteryx long bones are composed of nearly avascular parallel-fibered bone. This is among the slowest growing osseous tissues and is common in ectothermic reptiles. These findings dispute the hypothesis that non-avialan dinosaur growth and physiology were inherited in totality by the first birds. Examining these findings in a phylogenetic context required intensive sampling of outgroup dinosaurs and basalmost birds. Our results demonstrate the presence of a scale-dependent maniraptoran histological continuum that Archaeopteryx and other basalmost birds follow. Growth analysis for Archaeopteryx suggests that these animals showed exponential growth rates like non-avialan dinosaurs, three times slower than living precocial birds, but still within the lowermost range for all endothermic vertebrates.

CONCLUSIONS/SIGNIFICANCE: The unexpected histology of Archaeopteryx and other basalmost birds is actually consistent with retention of the phylogenetically earlier paravian dinosaur condition when size is considered. The first birds were simply feathered dinosaurs with respect to growth and energetic physiology. The evolution of the novel pattern in modern forms occurred later in the group's history.}, } @article {pmid19794491, year = {2009}, author = {Hu, D and Hou, L and Zhang, L and Xu, X}, title = {A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus.}, journal = {Nature}, volume = {461}, number = {7264}, pages = {640-643}, pmid = {19794491}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; *Birds/anatomy & histology/classification ; Calibration ; China ; Dinosaurs/*anatomy & histology/*classification ; Feathers/*anatomy & histology ; Flight, Animal ; Foot/anatomy & histology ; *Fossils ; Metatarsus/*anatomy & histology ; Phylogeny ; }, abstract = {The early evolution of the major groups of derived non-avialan theropods is still not well understood, mainly because of their poor fossil record in the Jurassic. A well-known result of this problem is the 'temporal paradox' argument that is sometimes made against the theropod hypothesis of avian origins. Here we report on an exceptionally well-preserved small theropod specimen collected from the earliest Late Jurassic Tiaojishan Formation of western Liaoning, China. The specimen is referable to the Troodontidae, which are among the theropods most closely related to birds. This new find refutes the 'temporal paradox'1 and provides significant information on the temporal framework of theropod divergence. Furthermore, the extensive feathering of this specimen, particularly the attachment of long pennaceous feathers to the pes, sheds new light on the early evolution of feathers and demonstrates the complex distribution of skeletal and integumentary features close to the dinosaur-bird transition.}, } @article {pmid19794481, year = {2009}, author = {Witmer, LM}, title = {Palaeontology: Feathered dinosaurs in a tangle.}, journal = {Nature}, volume = {461}, number = {7264}, pages = {601-602}, pmid = {19794481}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; *Birds/anatomy & histology/classification/physiology ; China ; Dinosaurs/*anatomy & histology/classification/physiology ; Feathers/*anatomy & histology/physiology ; Flight, Animal ; Foot/anatomy & histology/physiology ; *Fossils ; History, Ancient ; Phylogeny ; }, } @article {pmid19710052, year = {2010}, author = {Vinther, J and Briggs, DE and Clarke, J and Mayr, G and Prum, RO}, title = {Structural coloration in a fossil feather.}, journal = {Biology letters}, volume = {6}, number = {1}, pages = {128-131}, pmid = {19710052}, issn = {1744-957X}, mesh = {Animals ; Birds/*anatomy & histology/physiology ; Color ; Feathers/physiology/*ultrastructure ; *Fossils ; Germany ; Melanosomes/physiology/*ultrastructure ; Microscopy, Electron, Scanning ; Pigmentation/*physiology ; }, abstract = {Investigation of feathers from the famous Middle Eocene Messel Oil Shale near Darmstadt, Germany shows that they are preserved as arrays of fossilized melanosomes, the surrounding beta-keratin having degraded. The majority of feathers are preserved as aligned rod-shaped eumelanosomes. In some, however, the barbules of the open pennaceous, distal portion of the feather vane are preserved as a continuous external layer of closely packed melanosomes enclosing loosely aligned melanosomes. This arrangement is similar to the single thin-film nanostructure that generates an iridescent, structurally coloured sheen on the surface of black feathers in many lineages of living birds. This is, to our knowledge, the first evidence of preservation of a colour-producing nanostructure in a fossil feather and confirms the potential for determining colour differences in ancient birds and other dinosaurs.}, } @article {pmid19581600, year = {2009}, author = {McNab, BK}, title = {Resources and energetics determined dinosaur maximal size.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {106}, number = {29}, pages = {12184-12188}, pmid = {19581600}, issn = {1091-6490}, mesh = {Amphibians/anatomy & histology ; Animals ; *Body Size ; Desert Climate ; Dinosaurs/*anatomy & histology/*physiology ; *Energy Metabolism ; Lizards/anatomy & histology ; Models, Anatomic ; }, abstract = {Some dinosaurs reached masses that were approximately 8 times those of the largest, ecologically equivalent terrestrial mammals. The factors most responsible for setting the maximal body size of vertebrates are resource quality and quantity, as modified by the mobility of the consumer, and the vertebrate's rate of energy expenditure. If the food intake of the largest herbivorous mammals defines the maximal rate at which plant resources can be consumed in terrestrial environments and if that limit applied to dinosaurs, then the large size of sauropods occurred because they expended energy in the field at rates extrapolated from those of varanid lizards, which are approximately 22% of the rates in mammals and 3.6 times the rates of other lizards of equal size. Of 2 species having the same energy income, the species that uses the most energy for mass-independent maintenance of necessity has a smaller size. The larger mass found in some marine mammals reflects a greater resource abundance in marine environments. The presumptively low energy expenditures of dinosaurs potentially permitted Mesozoic communities to support dinosaur biomasses that were up to 5 times those found in mammalian herbivores in Africa today. The maximal size of predatory theropods was approximately 8 tons, which if it reflected the maximal capacity to consume vertebrates in terrestrial environments, corresponds in predatory mammals to a maximal mass less than a ton, which is what is observed. Some coelurosaurs may have evolved endothermy in association with the evolution of feathered insulation and a small mass.}, } @article {pmid19505011, year = {2009}, author = {Bochkov, AV}, title = {[Origin and evolution of parasitism in mites of the infraorder Eleutherengona (Acari: Prostigmata). Report II. Superfamily Cheyletoidea].}, journal = {Parazitologiia}, volume = {43}, number = {2}, pages = {97-117}, pmid = {19505011}, issn = {0031-1847}, mesh = {Animals ; *Biological Evolution ; *Host-Parasite Interactions ; Mites/classification/*physiology ; Vertebrates/*parasitology ; }, abstract = {Cheyletoid mites are represented by two lineages being presumably monophyletic. The ancestor of Cheyletidae-Syringophilidae lineage probably was a predator preying on other arthropods. It is hypothesized that syringophilids originated from the common ancestor with Cheyletidae, which switched to preying in bird nests. In Cheyletidae, parasitism on birds and mammals originated independently in several phylogenetic lineages (tribes). All cheyletids are permanents ectoparasites, excluding mites of the tribe Chelonotini. In this tribe, immature instars and males are probably predators in squirrel nests. Cheyletoid lineage II is represented by exclusively permanent parasites of vertebrates belonging to three families Harpirhynchidae (Demodicidae-Psorergatidae). It is presumed from the wide distribution of these mites on birds (Harpirhynchidae) and mammals (Psorergatidae and Demodicidae), that the common ancestor of this branch could have occurred on the common ancestor of birds and mammals; however, switching during an early phase of host evolution can not be excluded. A possible reason for the absence of cheyletoids on recent reptiles (excluding snakes) involves peculiarities of their molting. The high probability of loss of mites during reptile molting seems to have prevented original establishment of cheyletoid parasites on these hosts. These mites are probably absent also on crocodilians because of their aquatic mode of life. In birds, the skin has undergone significant evolutionary changes comparable to what is seen in the integument of mammals. This probably allowed to some cheyletoid mites of the family Harpirhynchidae to transfer to intradermal parasitism in capsules similar to those induced by species of Psorergatidae. The indirect argument of the long-time parasitic relationships between vertebrates and cheyletoids serves a find of mite eggs on the dinosaur's feathers from Lower Cretaceous period (northeast Brazil) (Martill, Davis, 1998). Authors believed that these eggs were laid by feather mites (Astigmata: Psoroptidia). These rounded shape eggs, however, are more similar with those of Cheyletoidea, than with the boomerang-shape eggs of feather mites. The position of the subfamily Ophioptinae associated with snakes of the superfamily Colubroidea in the core of the family Harpirhynchidae (bird parasites) is explained by the switching of its ancestor from passerine birds. Certain snakes feed on nestlings and adult birds, and most of these preys are small passerine birds.}, } @article {pmid19295609, year = {2009}, author = {Zheng, XT and You, HL and Xu, X and Dong, ZM}, title = {An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures.}, journal = {Nature}, volume = {458}, number = {7236}, pages = {333-336}, pmid = {19295609}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; China ; Dentition ; Dinosaurs/*anatomy & histology/*classification ; Feathers/anatomy & histology ; Fossils ; History, Ancient ; Integumentary System/*anatomy & histology ; Phylogeny ; Skin/anatomy & histology ; Skull/anatomy & histology ; }, abstract = {Ornithischia is one of the two major groups of dinosaurs, with heterodontosauridae as one of its major clades. Heterodontosauridae is characterized by small, gracile bodies and a problematic phylogenetic position. Recent phylogenetic work indicates that it represents the most basal group of all well-known ornithischians. Previous heterodontosaurid records are mainly from the Early Jurassic period (205-190 million years ago) of Africa. Here we report a new heterodontosaurid, Tianyulong confuciusi gen. et sp. nov., from the Early Cretaceous period (144-99 million years ago) of western Liaoning Province, China. Tianyulong extends the geographical distribution of heterodontosaurids to Asia and confirms the clade's previously questionable temporal range extension into the Early Cretaceous period. More surprisingly, Tianyulong bears long, singular and unbranched filamentous integumentary (outer skin) structures. This represents the first confirmed report, to our knowledge, of filamentous integumentary structures in an ornithischian dinosaur.}, } @article {pmid19295598, year = {2009}, author = {Witmer, LM}, title = {Dinosaurs: Fuzzy origins for feathers.}, journal = {Nature}, volume = {458}, number = {7236}, pages = {293-295}, pmid = {19295598}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; China ; Dinosaurs/*anatomy & histology/classification ; Feathers/*anatomy & histology ; Fossils ; History, Ancient ; Phylogeny ; Skin/*anatomy & histology ; }, } @article {pmid19289829, year = {2009}, author = {Longrich, NR and Currie, PJ}, title = {A microraptorine (Dinosauria-Dromaeosauridae) from the Late Cretaceous of North America.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {106}, number = {13}, pages = {5002-5007}, pmid = {19289829}, issn = {1091-6490}, mesh = {Animals ; Dinosaurs/anatomy & histology/*classification/genetics ; *Fossils ; North America ; Paleontology/methods ; Phylogeny ; Predatory Behavior ; }, abstract = {The fossil assemblages of the Late Cretaceous of North America are dominated by large-bodied dinosaur species. Associated skeletons of small dinosaurs are exceedingly rare, and small (<10 kg) carnivorous theropods have not previously been reported from these beds. Here, we describe a small dromaeosaurid from the 75-million-year-old Dinosaur Park Formation of Alberta, Canada. Hesperonychus elizabethae gen. et sp. nov. is represented by a pelvic girdle from an animal weighing approximately 1,900 g. Despite its size, the pubes and ilia are coossified, indicating that the animal was somatically mature. This is the smallest carnivorous, nonavian dinosaur known from North America. Phylogenetic analysis of Hesperonychus reveals that it is not closely related to previously described North American dromaeosaurids. Instead, Hesperonychus is a member of the dromaeosaurid clade Microraptorinae, a group containing the 4-winged Microraptor and the feathered Sinornithosaurus, both from the Lower Cretaceous Jehol Group of China. Hesperonychus is the youngest known member of this lineage, extending the temporal range of the clade by 45 million years, and it is the first microraptorine known from North America, providing further evidence for an affinity between the dinosaur faunas of North America and Asia. Study of fossil collections from the Dinosaur Park and Oldman formations of Alberta has revealed numerous isolated bones of small, basal dromaeosaurids, which are tentatively referred to Hesperonychus. These fossils suggest that small dromaeosaurids were a significant component of the carnivore community in this Late Cretaceous biota.}, } @article {pmid19139401, year = {2009}, author = {Xu, X and Zheng, X and You, H}, title = {A new feather type in a nonavian theropod and the early evolution of feathers.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {106}, number = {3}, pages = {832-834}, pmid = {19139401}, issn = {1091-6490}, mesh = {Animals ; *Biological Evolution ; Dinosaurs/*anatomy & histology/classification ; Feathers/*anatomy & histology ; }, abstract = {All described feathers in nonavian theropods are composite structures formed by multiple filaments. They closely resemble relatively advanced stages predicted by developmental models of the origin of feathers, but not the earliest stage. Here, we report a feather type in two specimens of the basal therizinosaur Beipiaosaurus, in which each individual feather is represented by a single broad filament. This morphotype is congruent with the stage I morphology predicted by developmental models, and all major predicted morphotypes have now been documented in the fossil record. This congruence between the full range of paleontological and developmental data strongly supports the hypothesis that feathers evolved and initially diversified in nonavian theropods before the origin of birds and the evolution of flight.}, } @article {pmid18948955, year = {2008}, author = {Zhang, F and Zhou, Z and Xu, X and Wang, X and Sullivan, C}, title = {A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers.}, journal = {Nature}, volume = {455}, number = {7216}, pages = {1105-1108}, doi = {10.1038/nature07447}, pmid = {18948955}, issn = {1476-4687}, mesh = {Animals ; China ; Dinosaurs/*anatomy & histology/*classification ; Feathers/*anatomy & histology ; *Fossils ; History, Ancient ; Phylogeny ; }, abstract = {Recent coelurosaurian discoveries have greatly enriched our knowledge of the transition from dinosaurs to birds, but all reported taxa close to this transition are from relatively well known coelurosaurian groups. Here we report a new basal avialan, Epidexipteryx hui gen. et sp. nov., from the Middle to Late Jurassic of Inner Mongolia, China. This new species is characterized by an unexpected combination of characters seen in several different theropod groups, particularly the Oviraptorosauria. Phylogenetic analysis shows it to be the sister taxon to Epidendrosaurus, forming a new clade at the base of Avialae. Epidexipteryx also possesses two pairs of elongate ribbon-like tail feathers, and its limbs lack contour feathers for flight. This finding shows that a member of the avialan lineage experimented with integumentary ornamentation as early as the Middle to Late Jurassic, and provides further evidence relating to this aspect of the transition from non-avian theropods to birds.}, } @article {pmid18611841, year = {2008}, author = {Vinther, J and Briggs, DE and Prum, RO and Saranathan, V}, title = {The colour of fossil feathers.}, journal = {Biology letters}, volume = {4}, number = {5}, pages = {522-525}, pmid = {18611841}, issn = {1744-9561}, mesh = {Animals ; *Birds ; Color ; *Dinosaurs ; *Feathers/ultrastructure ; *Fossils ; Melanins/isolation & purification ; *Melanosomes/ultrastructure ; }, abstract = {Feathers are complex integumentary appendages of birds and some other theropod dinosaurs. They are frequently coloured and function in camouflage and display. Previous investigations have concluded that fossil feathers are preserved as carbonized traces composed of feather-degrading bacteria. Here, an investigation of a colour-banded feather from the Lower Cretaceous Crato Formation of Brazil revealed that the dark bands are preserved as elongate, oblate carbonaceous bodies 1-2 microm long, whereas the light bands retain only relief traces on the rock matrix. Energy dispersive X-ray analysis showed that the dark bands preserve a substantial amount of carbon, whereas the light bands show no carbon residue. Comparison of these oblate fossil bodies with the structure of black feathers from a living bird indicates that they are the eumelanin-containing melanosomes. We conclude that most fossil feathers are preserved as melanosomes, and that the distribution of these structures in fossil feathers can preserve the colour pattern in the original feather. The discovery of preserved melanosomes opens up the possibility of interpreting the colour of extinct birds and other dinosaurs.}, } @article {pmid18494157, year = {2008}, author = {Kurochkin, EN and Bogdanovich, IA}, title = {[The origin of avian flight: conciliatory and systemic approaches].}, journal = {Izvestiia Akademii nauk. Seriia biologicheskaia}, volume = {}, number = {1}, pages = {5-17}, pmid = {18494157}, issn = {1026-3470}, mesh = {Animals ; *Biological Evolution ; Birds/genetics/*physiology ; Dinosaurs/genetics/physiology ; Extremities/physiology ; Flight, Animal/*physiology ; Fossils ; Paleontology ; *Phylogeny ; Tail/physiology ; }, abstract = {Based on evolutionary morphological analysis of the fore and hind limbs of extinct and extant birds, a new compromise hypothesis of the origin of flight in birds and theropod dinosaurs is proposed. The bipedalism and anisodactylous foot suitable for various functions were key adaptations for the development of flight. The bipedalism freed forelimbs from the supporting function and promoted transformation into wings, as animals moved from one tree branch to another and descended from trees. At the initial stage, the strong hind limbs provided the opportunity to climb and leap onto trees, bushes, or eminence, while the anisodactylous foot provided a firm support on both dry land and trees. The support provided by this foot allowed the reduction of the tail, which was initially composed of a long row of caudal vertebrae. Thus, a stage of gliding flight was not necessarily passed by early birds. In the other lineages of feathered creatures, functional changes in forelimbs that resulted in the formation of wings developed in parallel and followed almost the same scenario.}, } @article {pmid18482257, year = {2008}, author = {Axelsson, E and Hultin-Rosenberg, L and Brandström, M and Zwahlén, M and Clayton, DF and Ellegren, H}, title = {Natural selection in avian protein-coding genes expressed in brain.}, journal = {Molecular ecology}, volume = {17}, number = {12}, pages = {3008-3017}, doi = {10.1111/j.1365-294X.2008.03795.x}, pmid = {18482257}, issn = {1365-294X}, mesh = {Animals ; Avian Proteins/classification/*genetics ; Brain/*metabolism ; Evolution, Molecular ; *Gene Expression Profiling ; Phylogeny ; *Selection, Genetic ; }, abstract = {The evolution of birds from theropod dinosaurs took place approximately 150 million years ago, and was associated with a number of specific adaptations that are still evident among extant birds, including feathers, song and extravagant secondary sexual characteristics. Knowledge about the molecular evolutionary background to such adaptations is lacking. Here, we analyse the evolution of > 5000 protein-coding gene sequences expressed in zebra finch brain by comparison to orthologous sequences in chicken. Mean d(N)/d(S) is 0.085 and genes with their maximal expression in the eye and central nervous system have the lowest mean d(N)/d(S) value, while those expressed in digestive and reproductive tissues exhibit the highest. We find that fast-evolving genes (those which have higher than expected rate of nonsynonymous substitution, indicative of adaptive evolution) are enriched for biological functions such as fertilization, muscle contraction, defence response, response to stress, wounding and endogenous stimulus, and cell death. After alignment to mammalian orthologues, we identify a catalogue of 228 genes that show a significantly higher rate of protein evolution in the two bird lineages than in mammals. These accelerated bird genes, representing candidates for avian-specific adaptations, include genes implicated in vocal learning and other cognitive processes. Moreover, colouration genes evolve faster in birds than in mammals, which may have been driven by sexual selection for extravagant plumage characteristics.}, } @article {pmid18285280, year = {2008}, author = {Perrichot, V and Marion, L and Néraudeau, D and Vullo, R and Tafforeau, P}, title = {The early evolution of feathers: fossil evidence from Cretaceous amber of France.}, journal = {Proceedings. Biological sciences}, volume = {275}, number = {1639}, pages = {1197-1202}, pmid = {18285280}, issn = {0962-8452}, mesh = {*Amber ; Animals ; *Biological Evolution ; *Feathers ; *Fossils ; France ; }, abstract = {The developmental stages of feathers are of major importance in the evolution of body covering and the origin of avian flight. Until now, there were significant gaps in knowledge of early morphologies in theoretical stages of feathers as well as in palaeontological material. Here we report fossil evidence of an intermediate and critical stage in the incremental evolution of feathers which has been predicted by developmental theories but hitherto undocumented by evidence from both the recent and the fossil records. Seven feathers have been found in an Early Cretaceous (Late Albian, ca 100 Myr) amber of western France, which display a flattened shaft composed by the still distinct and incompletely fused bases of the barbs forming two irregular vanes. Considering their remarkably primitive features, and since recent discoveries have yielded feathers of modern type in some derived theropod dinosaurs, the Albian feathers from France might have been derived either from an early bird or from a non-avian dinosaur.}, } @article {pmid17885130, year = {2007}, author = {Turner, AH and Makovicky, PJ and Norell, MA}, title = {Feather quill knobs in the dinosaur Velociraptor.}, journal = {Science (New York, N.Y.)}, volume = {317}, number = {5845}, pages = {1721}, doi = {10.1126/science.1145076}, pmid = {17885130}, issn = {1095-9203}, mesh = {Animals ; Dinosaurs/*anatomy & histology ; *Feathers ; Fossils ; }, abstract = {Some nonavian theropod dinosaurs were at least partially covered in feathers or filamentous protofeathers. However, a complete understanding of feather distribution among theropod dinosaurs is limited because feathers are typically preserved only in lagerstätten like that of Solnhofen, Germany or Liaoning, China. Such deposits possess clear taphonomic biases toward small-bodied animals, limiting our knowledge regarding feather presence in larger members of feathered clades. We present direct evidence of feathers in Velociraptor mongoliensis based on the presence of quill knobs on the posterior forearm. This report of secondaries in a larger-bodied, derived, and clearly flightless member of a nonavian theropod clade represented by feathered relatives is a substantial contribution to our knowledge of the evolution of feathers.}, } @article {pmid17565365, year = {2007}, author = {Xu, X and Tan, Q and Wang, J and Zhao, X and Tan, L}, title = {A gigantic bird-like dinosaur from the Late Cretaceous of China.}, journal = {Nature}, volume = {447}, number = {7146}, pages = {844-847}, doi = {10.1038/nature05849}, pmid = {17565365}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology/*classification ; Body Size ; China ; Dinosaurs/*anatomy & histology/*classification ; History, Ancient ; Phylogeny ; Skeleton ; Time Factors ; }, abstract = {An evolutionary trend of decreasing size is present along the line to birds in coelurosaurian theropod evolution, but size increases are seen in many coelurosaurian subgroups, in which large forms are less bird-like. Here we report on a new non-avian dinosaur, Gigantoraptor erlianensis, gen. et sp. nov., from the Late Cretaceous Iren Dabasu Formation of Nei Mongol, China. Although it has a body mass of about 1,400 kg, a phylogenetic analysis positions this new taxon within the Oviraptorosauria, a group of small, feathered theropods rarely exceeding 40 kg in body mass. A histological analysis suggests that Gigantoraptor gained this size by a growth rate considerably faster than large North American tyrannosaurs such as Albertosaurus and Gorgosaurus. Gigantoraptor possesses several salient features previously unknown in any other dinosaur and its hind limb bone scaling and proportions are significantly different from those of other coelurosaurs, thus increasing the morphological diversity among dinosaurs. Most significantly, the gigantic Gigantoraptor shows many bird-like features absent in its smaller oviraptorosaurian relatives, unlike the evolutionary trend seen in many other coelurosaurian subgroups.}, } @article {pmid17521978, year = {2007}, author = {Lingham-Soliar, T and Feduccia, A and Wang, X}, title = {A new Chinese specimen indicates that 'protofeathers' in the Early Cretaceous theropod dinosaur Sinosauropteryx are degraded collagen fibres.}, journal = {Proceedings. Biological sciences}, volume = {274}, number = {1620}, pages = {1823-1829}, pmid = {17521978}, issn = {0962-8452}, mesh = {Animals ; Biological Evolution ; China ; Collagen/*chemistry/*metabolism ; Dinosaurs/*anatomy & histology ; Feathers/*chemistry ; *Fossils ; History, Ancient ; Skin/anatomy & histology ; }, abstract = {Alleged primitive feathers or protofeathers in the theropod dinosaur Sinosauropteryx have potentially profound implications concerning feather morphogenesis, evolution offlight, dinosaur physiology and perhaps even the origin of birds, yet their existence has never been adequately documented. We report on a new specimen of Sinosauropteryx which shows that the integumental structures proposed as protofeathers are the remains of structural fibres that provide toughness. The preservation in the proximal tail area reveals an architecture of closely associated bands offibres parallel to the tail's long axis, which originate from the skin. In adjacent more exposed areas, the fibres are short, fragmented and disorganized. Fibres preserved dorsal to the neck and back and in the distal part of the tail are the remains of a stiffening system of a frill, peripheral to the body and extending from the head to the tip of the tail. These findings are confirmed in the holotype Sinosauropteryx and NIGP 127587. The fibres show a striking similarity to the structure and levels of organization of dermal collagen. The proposal that these fibres are protofeathers is dismissed.}, } @article {pmid17344851, year = {2007}, author = {Organ, CL and Shedlock, AM and Meade, A and Pagel, M and Edwards, SV}, title = {Origin of avian genome size and structure in non-avian dinosaurs.}, journal = {Nature}, volume = {446}, number = {7132}, pages = {180-184}, doi = {10.1038/nature05621}, pmid = {17344851}, issn = {1476-4687}, support = {F32 GM075490/GM/NIGMS NIH HHS/United States ; }, mesh = {Animals ; Birds/*genetics/physiology ; Cell Size ; Dinosaurs/*genetics/physiology ; *Evolution, Molecular ; Genome/*genetics ; Haploidy ; Osteocytes/cytology ; Phylogeny ; }, abstract = {Avian genomes are small and streamlined compared with those of other amniotes by virtue of having fewer repetitive elements and less non-coding DNA. This condition has been suggested to represent a key adaptation for flight in birds, by reducing the metabolic costs associated with having large genome and cell sizes. However, the evolution of genome architecture in birds, or any other lineage, is difficult to study because genomic information is often absent for long-extinct relatives. Here we use a novel bayesian comparative method to show that bone-cell size correlates well with genome size in extant vertebrates, and hence use this relationship to estimate the genome sizes of 31 species of extinct dinosaur, including several species of extinct birds. Our results indicate that the small genomes typically associated with avian flight evolved in the saurischian dinosaur lineage between 230 and 250 million years ago, long before this lineage gave rise to the first birds. By comparison, ornithischian dinosaurs are inferred to have had much larger genomes, which were probably typical for ancestral Dinosauria. Using comparative genomic data, we estimate that genome-wide interspersed mobile elements, a class of repetitive DNA, comprised 5-12% of the total genome size in the saurischian dinosaur lineage, but was 7-19% of total genome size in ornithischian dinosaurs, suggesting that repetitive elements became less active in the saurischian lineage. These genomic characteristics should be added to the list of attributes previously considered avian but now thought to have arisen in non-avian dinosaurs, such as feathers, pulmonary innovations, and parental care and nesting.}, } @article {pmid17242354, year = {2007}, author = {Chatterjee, S and Templin, RJ}, title = {Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {104}, number = {5}, pages = {1576-1580}, pmid = {17242354}, issn = {0027-8424}, mesh = {Animals ; *Biological Evolution ; Biomechanical Phenomena ; Dinosaurs/*anatomy & histology/*physiology ; *Feathers ; *Flight, Animal ; Fossils ; Models, Biological ; Paleontology ; Phylogeny ; Reptiles ; Wings, Animal/*physiology ; }, abstract = {Microraptor gui, a four-winged dromaeosaur from the Early Cretaceous of China, provides strong evidence for an arboreal-gliding origin of avian flight. It possessed asymmetric flight feathers not only on the manus but also on the pes. A previously published reconstruction shows that the hindwing of Microraptor supported by a laterally extended leg would have formed a second pair of wings in tetrapteryx fashion. However, this wing design conflicts with known theropod limb joints that entail a parasagittal posture of the hindlimb. Here, we offer an alternative planform of the hindwing of Microraptor that is concordant with its feather orientation for producing lift and normal theropod hindlimb posture. In this reconstruction, the wings of Microraptor could have resembled a staggered biplane configuration during flight, where the forewing formed the dorsal wing and the metatarsal wing formed the ventral one. The contour feathers on the tibia were positioned posteriorly, oriented in a vertical plane for streamlining that would reduce the drag considerably. Leg feathers are present in many fossil dromaeosaurs, early birds, and living raptors, and they play an important role in flight during catching and carrying prey. A computer simulation of the flight performance of Microraptor suggests that its biplane wings were adapted for undulatory "phugoid" gliding between trees, where the horizontal feathered tail offered additional lift and stability and controlled pitch. Like the Wright 1903 Flyer, Microraptor, a gliding relative of early birds, took to the air with two sets of wings.}, } @article {pmid17148248, year = {2007}, author = {Schweitzer, MH and Wittmeyer, JL and Horner, JR}, title = {Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous to the present.}, journal = {Proceedings. Biological sciences}, volume = {274}, number = {1607}, pages = {183-197}, pmid = {17148248}, issn = {0962-8452}, mesh = {Animals ; Birds/*anatomy & histology ; Blood Vessels/*cytology ; Bone Demineralization Technique ; Bone and Bones/blood supply/*cytology ; Dinosaurs/*anatomy & histology ; *Fossils ; Mammals/*anatomy & histology ; Paleontology/*methods ; }, abstract = {Soft tissues and cell-like microstructures derived from skeletal elements of a well-preserved Tyrannosaurus rex (MOR 1125) were represented by four components in fragments of demineralized cortical and/or medullary bone: flexible and fibrous bone matrix; transparent, hollow and pliable blood vessels; intravascular material, including in some cases, structures morphologically reminiscent of vertebrate red blood cells; and osteocytes with intracellular contents and flexible filipodia. The present study attempts to trace the occurrence of these four components in bone from specimens spanning multiple geological time periods and varied depositional environments. At least three of the four components persist in some skeletal elements of specimens dating to the Campanian. Fibrous bone matrix is more altered over time in morphology and less likely to persist than vessels and/or osteocytes. Vessels vary greatly in preservation, even within the same specimen, with some regions retaining pliability and other regions almost crystalline. Osteocytes also vary, with some retaining long filipodia and transparency, while others present with short and stubby filipodia and deeply pigmented nuclei, or are pigmented throughout with no nucleus visible. Alternative hypotheses are considered to explain the origin/source of observed materials. Finally, a two-part mechanism, involving first cross-linking of molecular components and subsequent mineralization, is proposed to explain the surprising presence of still-soft elements in fossil bone. These results suggest that present models of fossilization processes may be incomplete and that soft tissue elements may be more commonly preserved, even in older specimens, than previously thought. Additionally, in many cases, osteocytes with defined nuclei are preserved, and may represent an important source for informative molecular data.}, } @article {pmid17049829, year = {2006}, author = {Lin, CM and Jiang, TX and Widelitz, RB and Chuong, CM}, title = {Molecular signaling in feather morphogenesis.}, journal = {Current opinion in cell biology}, volume = {18}, number = {6}, pages = {730-741}, pmid = {17049829}, issn = {0955-0674}, support = {R01 AR042177-11/AR/NIAMS NIH HHS/United States ; AR052397/AR/NIAMS NIH HHS/United States ; R01 AR052397/AR/NIAMS NIH HHS/United States ; K01 AR002177/AR/NIAMS NIH HHS/United States ; AR47364/AR/NIAMS NIH HHS/United States ; R01 AR042177/AR/NIAMS NIH HHS/United States ; R01 AR047364/AR/NIAMS NIH HHS/United States ; R01 AR047364-04/AR/NIAMS NIH HHS/United States ; AR2177/AR/NIAMS NIH HHS/United States ; R01 AR042177-12/AR/NIAMS NIH HHS/United States ; R01 AR047364-05/AR/NIAMS NIH HHS/United States ; }, mesh = {Animals ; Body Patterning/physiology ; Ectoderm/cytology/metabolism ; Feathers/cytology/*embryology/metabolism ; Gene Expression Regulation, Developmental/physiology ; Genes, Homeobox/genetics ; Models, Biological ; Morphogenesis/*physiology ; Regeneration/physiology ; Skin/cytology/*embryology/metabolism ; }, abstract = {The development and regeneration of feathers have gained much attention recently because of progress in the following areas. First, pattern formation. The exquisite spatial arrangement provides a simple model for decoding the rules of morphogenesis. Second, stem cell biology. In every molting, a few stem cells have to rebuild the entire epithelial organ, providing much to learn on how to regenerate an organ physiologically. Third, evolution and development ('Evo-Devo'). The discovery of feathered dinosaur fossils in China prompted enthusiastic inquiries about the origin and evolution of feathers. Progress has been made in elucidating feather morphogenesis in five successive phases: macro-patterning, micro-patterning, intra-bud morphogenesis, follicle morphogenesis and regenerative cycling.}, } @article {pmid16713939, year = {2006}, author = {Clarke, J and Middleton, K}, title = {Bird evolution.}, journal = {Current biology : CB}, volume = {16}, number = {10}, pages = {R350-4}, doi = {10.1016/j.cub.2006.04.023}, pmid = {16713939}, issn = {0960-9822}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology ; Dinosaurs ; Feathers ; Fossils ; }, } @article {pmid16541071, year = {2006}, author = {Göhlich, UB and Chiappe, LM}, title = {A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago.}, journal = {Nature}, volume = {440}, number = {7082}, pages = {329-332}, doi = {10.1038/nature04579}, pmid = {16541071}, issn = {1476-4687}, mesh = {Animals ; *Diet ; Dinosaurs/anatomy & histology/*classification/physiology ; Feathers ; Food Preferences ; *Fossils ; Germany ; History, Ancient ; Integumentary System/anatomy & histology ; *Meat ; Phylogeny ; Skeleton ; Skull/anatomy & histology ; Tail/anatomy & histology ; Time Factors ; }, abstract = {Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought.}, } @article {pmid16541058, year = {2006}, author = {Xu, X}, title = {Palaeontology: scales, feathers and dinosaurs.}, journal = {Nature}, volume = {440}, number = {7082}, pages = {287-288}, doi = {10.1038/440287a}, pmid = {16541058}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/physiology ; Dinosaurs/*anatomy & histology/*classification/physiology ; *Feathers ; *Fossils ; Germany ; History, Ancient ; Integumentary System/*anatomy & histology ; Phylogeny ; Skeleton ; Time Factors ; }, } @article {pmid16537135, year = {2006}, author = {Grimaldi, D and Engel, MS}, title = {Fossil Liposcelididae and the lice ages (Insecta: Psocodea).}, journal = {Proceedings. Biological sciences}, volume = {273}, number = {1586}, pages = {625-633}, pmid = {16537135}, issn = {0962-8452}, mesh = {Animals ; Dominican Republic ; Female ; *Fossils ; Myanmar ; Phthiraptera/*anatomy & histology/genetics ; Phylogeny ; }, abstract = {Fossilized, winged adults belonging to the psocopteran family Liposcelididae are reported in amber from the mid-Cretaceous (ca 100 Myr) of Myanmar (described as Cretoscelis burmitica, gen. et sp. n.) and the Miocene (ca 20 Myr) of the Dominican Republic (Belaphopsocus dominicus sp. n.). Cretoscelis is an extinct sister group to all other Liposcelididae and the family is the free-living sister group to the true lice (order Phthiraptera, all of which are ectoparasites of birds and mammals). A phylogenetic hypothesis of relationships among genera of Liposcelididae, including fossils, reveals perfect correspondence between the chronology of fossils and cladistic rank of taxa. Lice and Liposcelididae minimally diverged 100 Myr, perhaps even in the earliest Cretaceous 145 Myr or earlier, in which case the hosts of lice would have been early mammals, early birds and possibly other feathered theropod dinosaurs, as well as haired pterosaurs.}, } @article {pmid21395983, year = {2006}, author = {Xu, X}, title = {Feathered dinosaurs from China and the evolution of major avian characters.}, journal = {Integrative zoology}, volume = {1}, number = {1}, pages = {4-11}, doi = {10.1111/j.1749-4877.2006.00004.x}, pmid = {21395983}, issn = {1749-4869}, abstract = {Recent discoveries of feathered dinosaurs from Early Cretaceous deposits in Liaoning, China, have not only lent strongest support for the dinosaurian hypothesis of bird origins, but have also provided much-needed information about the origins of feathers and avian flight. Preliminary analysis of character evolution suggests that the major avian osteological characters were acquired during the early evolution of maniraptoran dinosaurs. The available evidence also suggests that the first feathers with a filamentous morphology probably evolved in basal coelurosaurs and pennaceous feathers (including those with aerodynamic features) were developed in non-avian maniraptorans, indicating that feathers evolved before the origin of birds and their flight. An evolutionary model is proposed here to describe the major stages of feather evolution, a process characterized by a combination of both transformational and innovative modifications. This model is different from some recent developmental models, which suggest that feathers are evolutionary novelties without a homologous relationship to reptilian scales. Although non-avian theropods are traditionally regarded as distinctly cursorial animals, recent discoveries suggest that the closest relatives of birds might be arboreal theropods. Many bird features, such as the furcula and pennaceous feathers, evolved in a terrestrial context, whereas others, such as some pedal modifications, may have evolved in an arboreal context. Consequently, arboreality may have also contributed to the origin of avian flight.}, } @article {pmid16344487, year = {2005}, author = {Zhou, Z and Zhang, F}, title = {Discovery of an ornithurine bird and its implication for Early Cretaceous avian radiation.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {102}, number = {52}, pages = {18998-19002}, pmid = {16344487}, issn = {0027-8424}, mesh = {Animals ; Biological Evolution ; Birds/*anatomy & histology/*classification ; Bone and Bones/anatomy & histology ; China ; Dinosaurs ; *Flight, Animal ; Fossils ; Paleontology ; Skeleton ; }, abstract = {An ornithurine bird, Hongshanornis longicresta gen. et sp. nov., represented by a nearly complete and articulated skeleton in full plumage, has been recovered from the lacustrine deposits of the Lower Cretaceous Jehol Group in Inner Mongolia, northeast China. The bird had completely reduced teeth and possessed a beak in both the upper and lower jaws, representing the earliest known beaked ornithurine. The preservation of a predentary bone confirms that this structure is not unique to ornithischian dinosaurs but was common in early ornithurine birds. This small bird had a strong flying capability with a low aspect ratio wing. It was probably a wader, feeding in shallow water or marshes. This find confirms that the aquatic environment had played a key role in the origin and early radiation of ornithurines, one branch of which eventually gave rise to extant birds near the Cretaceous/Tertiary boundary. This discovery provides important information not only for studying the origin and early evolution of ornithurines but also for understanding the differentiation in morphology, body size, and diet of the Early Cretaceous birds.}, } @article {pmid16322455, year = {2005}, author = {Mayr, G and Pohl, B and Peters, DS}, title = {A well-preserved Archaeopteryx specimen with theropod features.}, journal = {Science (New York, N.Y.)}, volume = {310}, number = {5753}, pages = {1483-1486}, doi = {10.1126/science.1120331}, pmid = {16322455}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; *Birds ; Bone and Bones ; *Dinosaurs ; Feathers ; *Fossils ; Germany ; Skeleton ; }, abstract = {A nearly complete skeleton of Archaeopteryx with excellent bone preservation shows that the osteology of the urvogel is similar to that of nonavian theropod dinosaurs. The new specimen confirms the presence of a hyperextendible second toe as in dromaeosaurs and troodontids. Archaeopteryx had a plesiomorphic tetraradiate palatine bone and no fully reversed first toe. These observations provide further evidence for the theropod ancestry of birds. In addition, the presence of a hyperextendible second toe blurs the distinction of archaeopterygids from basal deinonychosaurs (troodontids and dromaeosaurs) and challenges the monophyly of Aves.}, } @article {pmid16322436, year = {2005}, author = {Stokstad, E}, title = {Paleontology. Best Archaeopteryx fossil so far ruffles a few feathers.}, journal = {Science (New York, N.Y.)}, volume = {310}, number = {5753}, pages = {1418-1419}, doi = {10.1126/science.310.5753.1418}, pmid = {16322436}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; *Birds/anatomy & histology/classification ; Bone and Bones/anatomy & histology ; *Dinosaurs/anatomy & histology/classification ; Feathers ; *Fossils ; Germany ; }, } @article {pmid16292258, year = {2005}, author = {Padian, K and Dial, KP}, title = {Origin of flight: Could 'four-winged' dinosaurs fly?.}, journal = {Nature}, volume = {438}, number = {7066}, pages = {E3; discussion E3-4}, doi = {10.1038/nature04354}, pmid = {16292258}, issn = {1476-4687}, mesh = {Animals ; *Biological Evolution ; Biomechanical Phenomena ; Birds/anatomy & histology/physiology ; China ; Dinosaurs/*anatomy & histology/*physiology ; Feathers/anatomy & histology/*physiology ; Flight, Animal/*physiology ; Fossils ; Hindlimb/anatomy & histology/physiology ; History, Ancient ; Models, Biological ; Phylogeny ; Reproducibility of Results ; Wings, Animal/*anatomy & histology/*physiology ; }, abstract = {Our understanding of the origin of birds, feathers and flight has been greatly advanced by new discoveries of feathered non-avian dinosaurs, but functional analyses have not kept pace with taxonomic descriptions. Zhang and Zhou describe feathers on the tibiotarsus of a new basal enantiornithine bird from the Early Cretaceous of China. They infer, as did Xu and colleagues from similar feathers on the small non-avian theropod Microraptor found in similar deposits, that these leg feathers had aerodynamic properties and so might have been used in some kind of flight.}, } @article {pmid16217748, year = {2005}, author = {Feduccia, A and Lingham-Soliar, T and Hinchliffe, JR}, title = {Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence.}, journal = {Journal of morphology}, volume = {266}, number = {2}, pages = {125-166}, doi = {10.1002/jmor.10382}, pmid = {16217748}, issn = {0362-2525}, mesh = {Animals ; Biological Evolution ; Chick Embryo ; Chondroitin Sulfates/biosynthesis ; Collagen/analysis ; Dinosaurs/*anatomy & histology ; Dolphins/anatomy & histology ; Feathers/*anatomy & histology/cytology/growth & development ; Fossils ; Integumentary System/anatomy & histology ; *Models, Biological ; Morphogenesis ; *Paleontology ; Phylogeny ; Reptiles/anatomy & histology ; Sharks/anatomy & histology ; Wings, Animal/anatomy & histology ; }, abstract = {The origin of birds and avian flight from within the archosaurian radiation has been among the most contentious issues in paleobiology. Although there is general agreement that birds are related to theropod dinosaurs at some level, debate centers on whether birds are derived directly from highly derived theropods, the current dogma, or from an earlier common ancestor lacking suites of derived anatomical characters. Recent discoveries from the Early Cretaceous of China have highlighted the debate, with claims of the discovery of all stages of feather evolution and ancestral birds (theropod dinosaurs), although the deposits are at least 25 million years younger than those containing the earliest known bird Archaeopteryx. In the first part of the study we examine the fossil evidence relating to alleged feather progenitors, commonly referred to as protofeathers, in these putative ancestors of birds. Our findings show no evidence for the existence of protofeathers and consequently no evidence in support of the follicular theory of the morphogenesis of the feather. Rather, based on histological studies of the integument of modern reptiles, which show complex patterns of the collagen fibers of the dermis, we conclude that "protofeathers" are probably the remains of collagenous fiber "meshworks" that reinforced the dinosaur integument. These "meshworks" of the skin frequently formed aberrant patterns resembling feathers as a consequence of decomposition. Our findings also draw support from new paleontological evidence. We describe integumental structures, very similar to "protofeathers," preserved within the rib area of a Psittacosaurus specimen from Nanjing, China, an ornithopod dinosaur unconnected with the ancestry of birds. These integumental structures show a strong resemblance to the collagenous fiber systems in the dermis of many animals. We also report the presence of scales in the forearm of the theropod ornithomimid (bird mimic) dinosaur, Pelecanimimus, from Spain. In the second part of the study we examine evidence relating to the most critical character thought to link birds to derived theropods, a tridactyl hand composed of digits 1-2-3. We maintain the evidence supports interpretation of bird wing digit identity as 2,3,4, which appears different from that in theropod dinosaurs. The phylogenetic significance of Chinese microraptors is also discussed, with respect to bird origins and flight origins. We suggest that a possible solution to the disparate data is that Aves plus bird-like maniraptoran theropods (e.g., microraptors and others) may be a separate clade, distinctive from the main lineage of Theropoda, a remnant of the early avian radiation, exhibiting all stages of flight and flightlessness.}, } @article {pmid16158273, year = {2005}, author = {Buffetaut, E and Grellet-Tinner, G and Suteethorn, V and Cuny, G and Tong, H and Kosir, A and Cavin, L and Chitsing, S and Griffiths, PJ and Tabouelle, J and Le Loeuff, J}, title = {Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition.}, journal = {Die Naturwissenschaften}, volume = {92}, number = {10}, pages = {477-482}, pmid = {16158273}, issn = {0028-1042}, mesh = {Animals ; Birds/*anatomy & histology/embryology ; China ; Dinosaurs/*anatomy & histology/embryology ; Embryo, Nonmammalian ; Female ; *Fossils ; Microscopy, Electron, Scanning ; Ovum/ultrastructure ; *Paleontology ; Thailand ; }, abstract = {We report on very small fossil eggs from the Lower Cretaceous of Thailand, one of them containing a theropod embryo, which display a remarkable mosaic of characters. While the surficial ornamentation is typical of non-avian saurischian dinosaurs, the three-layered prismatic structure of the eggshell is currently known only in extant and fossil eggs associated with birds. These eggs, about the size of a goldfinch's, mirror at the reproductive level the retention of small body size that was paramount in the transition from non-avian theropods to birds. The egg-layer may have been a small feathered theropod similar to those recently found in China.}, } @article {pmid15875020, year = {2005}, author = {Kirkland, JI and Zanno, LE and Sampson, SD and Clark, JM and DeBlieux, DD}, title = {A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah.}, journal = {Nature}, volume = {435}, number = {7038}, pages = {84-87}, doi = {10.1038/nature03468}, pmid = {15875020}, issn = {1476-4687}, mesh = {Animals ; Dinosaurs/*anatomy & histology/*classification ; *Fossils ; History, Ancient ; Phylogeny ; *Skeleton ; Skull/anatomy & histology ; Species Specificity ; Tooth/anatomy & histology ; Utah ; }, abstract = {Therizinosauroids are an enigmatic group of dinosaurs known mostly from the Cretaceous period of Asia, whose derived members are characterized by elongate necks, laterally expanded pelves, small, leaf-shaped teeth, edentulous rostra and mandibular symphyses that probably bore keratinized beaks. Although more than a dozen therizinosauroid taxa are known, their relationships within Dinosauria have remained controversial because of fragmentary remains and an unusual suite of characters. The recently discovered 'feathered' therizinosauroid Beipiaosaurus from the Early Cretaceous of China helped to clarify the theropod affinities of the group. However, Beipiaosaurus is also poorly represented. Here we describe a new, primitive therizinosauroid from an extensive paucispecific bonebed at the base of the Cedar Mountain Formation (Early Cretaceous) of east-central Utah. This new taxon represents the most complete and most basal therizinosauroid yet discovered. Phylogenetic analysis of coelurosaurian theropods incorporating this taxon places it at the base of the clade Therizinosauroiden, indicating that this species documents the earliest known stage in the poorly understood transition from carnivory to herbivory within Therizinosauroidea. The taxon provides the first documentation, to our knowledge, of therizinosauroids in North America during the Early Cretaceous.}, } @article {pmid15685441, year = {2005}, author = {Xu, X and Zhang, F}, title = {A new maniraptoran dinosaur from China with long feathers on the metatarsus.}, journal = {Die Naturwissenschaften}, volume = {92}, number = {4}, pages = {173-177}, pmid = {15685441}, issn = {0028-1042}, mesh = {Animals ; China ; Dinosaurs/*anatomy & histology/classification ; Feathers/*anatomy & histology ; *Fossils ; Metatarsus/*anatomy & histology ; Paleontology ; Phylogeny ; }, abstract = {The unusual presence of long pennaceous feathers on the feet of basal dromaeosaurid dinosaurs has recently been presented as strong evidence in support of the arboreal-gliding hypothesis for the origin of bird flight, but it could be a unique feature of dromaeosaurids and thus irrelevant to the theropod-bird transition. Here, we report a new eumaniraptoran theropod from China, with avian affinities, which also has long pennaceous feathers on its feet. This suggests that such morphology might represent a primitive adaptation close to the theropod-bird transition. The long metatarsus feathers are likely primitive for Eumaniraptora and might have played an important role in the origin of avian flight.}, } @article {pmid15503987, year = {2004}, author = {Wappler, T and Smith, VS and Dalgleish, RC}, title = {Scratching an ancient itch: an Eocene bird louse fossil.}, journal = {Proceedings. Biological sciences}, volume = {271 Suppl 5}, number = {Suppl 5}, pages = {S255-8}, pmid = {15503987}, issn = {0962-8452}, mesh = {Animals ; Birds/parasitology ; *Fossils ; Germany ; Phthiraptera/*anatomy & histology/*classification ; *Phylogeny ; Species Specificity ; }, abstract = {Out of the 30 extant orders of insects, all but one, the parasitic lice (Insecta: Phthiraptera), have a confirmed fossil record. Here, we report the discovery of what appears to be the first bird louse fossil: an exceptionally well-preserved specimen collected from the crater of the Eckfeld maar near Manderscheid, Germany. The 44-million-year-old specimen shows close phylogenetic affinities with modern feather louse ectoparasites of aquatic birds. Preservation of feather remnants in the specimen's foregut confirms its association as a bird ectoparasite. Based on a phylogenetic analysis of the specimen and palaeoecological data, we suggest that this louse was the parasite of a large ancestor to modern Anseriformes (swans, geese and ducks) or Charadriiformes (shorebirds). The crown group position of this fossil in the phylogeny of lice confirms the group's long coevolutionary history with birds and points to an early origin for lice, perhaps inherited from early-feathered theropod dinosaurs.}, } @article {pmid15496911, year = {2004}, author = {Zhang, F and Zhou, Z}, title = {Palaeontology: leg feathers in an Early Cretaceous bird.}, journal = {Nature}, volume = {431}, number = {7011}, pages = {925}, doi = {10.1038/431925a}, pmid = {15496911}, issn = {1476-4687}, mesh = {Animals ; Birds/*anatomy & histology/classification/physiology ; China ; Dinosaurs/anatomy & histology ; Feathers/*anatomy & histology/physiology ; Flight, Animal ; *Fossils ; *Hindlimb/anatomy & histology ; Phylogeny ; Tail/anatomy & histology ; }, abstract = {Here we describe a fossil of an enantiornithine bird from the Early Cretaceous period in China that has substantial plumage feathers attached to its upper leg (tibiotarsus). The discovery could be important in view of the relative length and aerodynamic features of these leg feathers compared with those of the small 'four-winged' gliding dinosaur Microraptor and of the earliest known bird, Archaeopteryx. They may be remnants of earlier long, aerodynamic leg feathers, in keeping with the hypothesis that birds went through a four-winged stage during the evolution of flight.}, } @article {pmid15472048, year = {2004}, author = {Stokstad, E}, title = {Paleontology. T. rex clan evolved head first.}, journal = {Science (New York, N.Y.)}, volume = {306}, number = {5694}, pages = {211}, doi = {10.1126/science.306.5694.211a}, pmid = {15472048}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Body Constitution ; China ; Dinosaurs/*anatomy & histology ; Extremities/anatomy & histology ; Feathers/anatomy & histology ; *Fossils ; Skull/anatomy & histology ; }, } @article {pmid15470426, year = {2004}, author = {Xu, X and Norell, MA and Kuang, X and Wang, X and Zhao, Q and Jia, C}, title = {Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids.}, journal = {Nature}, volume = {431}, number = {7009}, pages = {680-684}, doi = {10.1038/nature02855}, pmid = {15470426}, issn = {1476-4687}, mesh = {Animals ; China ; Dinosaurs/*anatomy & histology/*classification ; Feathers/*anatomy & histology ; *Fossils ; Integumentary System/anatomy & histology ; Skeleton ; Skull/anatomy & histology ; }, abstract = {Tyrannosauroids are one of the last and the most successful large-bodied predatory dinosaur groups, but their early history remains poorly understood. Here we report a new basal tyrannosauroid from the Early Cretaceous Yixian Formation of western Liaoning, China, which is small and gracile and has relatively long arms with three-fingered hands. The new taxon is the earliest known unquestionable tyrannosauroid found so far. It shows a mosaic of characters, including a derived cranial structure resembling that of derived tyrannosauroids and a primitive postcranial skeleton similar to basal coelurosaurians. One of the specimens also preserves a filamentous integumentary covering similar to that of other coelurosaurian theropods from western Liaoning. This provides the first direct fossil evidence that tyrannosauroids had protofeathers.}, } @article {pmid15457223, year = {2004}, author = {Dalton, R}, title = {Feathers fly as China cracks down on illegal fossil sales.}, journal = {Nature}, volume = {431}, number = {7008}, pages = {496}, doi = {10.1038/431496b}, pmid = {15457223}, issn = {1476-4687}, mesh = {Animals ; Birds ; China ; Commerce/*economics/ethics/*legislation & jurisprudence ; *Dinosaurs ; *Fossils ; Internationality ; Research/economics/*standards ; }, } @article {pmid15365634, year = {2004}, author = {Zhou, Z}, title = {The origin and early evolution of birds: discoveries, disputes, and perspectives from fossil evidence.}, journal = {Die Naturwissenschaften}, volume = {91}, number = {10}, pages = {455-471}, pmid = {15365634}, issn = {0028-1042}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology/*classification ; China ; Feathers ; *Fossils ; Humans ; Image Processing, Computer-Assisted ; }, abstract = {The study of the origin and early evolution of birds has never produced as much excitement and public attention as in the past decade. Well preserved and abundant new fossils of birds and dinosaurs have provided unprecedented new evidence on the dinosaurian origin of birds, the arboreal origin of avian flight, and the origin of feathers prior to flapping flight. The Mesozoic avian assemblage mainly comprises two major lineages: the prevalent extinct group Enantiornithes, and the Ornithurae, which gave rise to all modern birds, as well as several more basal taxa. Cretaceous birds radiated into various paleoecological niches that included fish- and seed-eating. Significant size and morphological differences and variation in flight capabilities, ranging from gliding to powerful flight among early birds, highlight the diversification of birds in the Early Cretaceous. There is little evidence, however, to support a Mesozoic origin of modern avian groups. Controversy and debate, nevertheless, surround many of these findings, and more details are needed to give a better appreciation of the significance of these new discoveries.}, } @article {pmid15295597, year = {2004}, author = {Alonso, PD and Milner, AC and Ketcham, RA and Cookson, MJ and Rowe, TB}, title = {The avian nature of the brain and inner ear of Archaeopteryx.}, journal = {Nature}, volume = {430}, number = {7000}, pages = {666-669}, doi = {10.1038/nature02706}, pmid = {15295597}, issn = {1476-4687}, mesh = {Adaptation, Physiological ; Animals ; Birds/*anatomy & histology/physiology ; Brain/*anatomy & histology/physiology ; Dinosaurs/*anatomy & histology/physiology ; Ear, Inner/*anatomy & histology/physiology ; Flight, Animal ; *Fossils ; Skull/anatomy & histology ; }, abstract = {Archaeopteryx, the earliest known flying bird (avialan) from the Late Jurassic period, exhibits many shared primitive characters with more basal coelurosaurian dinosaurs (the clade including all theropods more bird-like than Allosaurus), such as teeth, a long bony tail and pinnate feathers. However, Archaeopteryx possessed asymmetrical flight feathers on its wings and tail, together with a wing feather arrangement shared with modern birds. This suggests some degree of powered flight capability but, until now, little was understood about the extent to which its brain and special senses were adapted for flight. We investigated this problem by computed tomography scanning and three-dimensional reconstruction of the braincase of the London specimen of Archaeopteryx. Here we show the reconstruction of the braincase from which we derived endocasts of the brain and inner ear. These suggest that Archaeopteryx closely resembled modern birds in the dominance of the sense of vision and in the possession of expanded auditory and spatial sensory perception in the ear. We conclude that Archaeopteryx had acquired the derived neurological and structural adaptations necessary for flight. An enlarged forebrain suggests that it had also developed enhanced somatosensory integration with these special senses demanded by a lifestyle involving flying ability.}, } @article {pmid15287100, year = {2004}, author = {Kundrát, M}, title = {When did theropods become feathered?--evidence for pre-Archaeopteryx feathery appendages.}, journal = {Journal of experimental zoology. Part B, Molecular and developmental evolution}, volume = {302}, number = {4}, pages = {355-364}, doi = {10.1002/jez.b.20014}, pmid = {15287100}, issn = {1552-5007}, mesh = {Animals ; *Biological Evolution ; Classification ; Dinosaurs/*anatomy & histology/classification ; Extremities/anatomy & histology ; Feathers/*anatomy & histology ; *Fossils ; Massachusetts ; }, abstract = {Filamentous impressions associated with locomotive theropod tracks in the Lower Jurassic Turners Falls Formation of western Massachusetts, U.S.A. represent the oldest evidence of feathered dinosaurs. Feather impressions are preserved with sitting traces which bear integumentary structures along the outlines of the pre-pubic and ischiadic impressions. Extant palaeognathous down feathers provide a valuable comparative model for these filamentous integumental structures and for similar structures described in Chinese theropods from younger deposits. The described morphologies are congruent with Stage II of Prum ('99) and support that plumulaceous morphologies evolved before the origin of the rhachis and the planar vane. Appearance of feathery appendages in theropods may be linked to evolution of higher metabolic rates, improved locomotory abilities, and/or distinct behavior(s) and visual communication. Development of feathery integument might have also played a crucial role in the competitiveness and successful radiation of maniraptoriform theropods and their actively flying descendants in the Jurassic.}, } @article {pmid15272390, year = {2004}, author = {Wu, P and Hou, L and Plikus, M and Hughes, M and Scehnet, J and Suksaweang, S and Widelitz, R and Jiang, TX and Chuong, CM}, title = {Evo-Devo of amniote integuments and appendages.}, journal = {The International journal of developmental biology}, volume = {48}, number = {2-3}, pages = {249-270}, pmid = {15272390}, issn = {0214-6282}, support = {R01 AR042177-07S1/AR/NIAMS NIH HHS/United States ; R01 AR047364-01A2/AR/NIAMS NIH HHS/United States ; R01 AR042177-08S1/AR/NIAMS NIH HHS/United States ; R01 AR042177-09/AR/NIAMS NIH HHS/United States ; R01 AR047364-02/AR/NIAMS NIH HHS/United States ; R01 AR042177-08/AR/NIAMS NIH HHS/United States ; R01 AR042177-07/AR/NIAMS NIH HHS/United States ; R01 AR042177/AR/NIAMS NIH HHS/United States ; R01 AR047364/AR/NIAMS NIH HHS/United States ; }, mesh = {Animals ; *Biological Evolution ; *Growth and Development ; Integumentary System/*embryology ; Morphogenesis ; Vertebrates/*embryology/*growth & development ; }, abstract = {Integuments form the boundary between an organism and the environment. The evolution of novel developmental mechanisms in integuments and appendages allows animals to live in diverse ecological environments. Here we focus on amniotes. The major achievement for reptile skin is an adaptation to the land with the formation of a successful barrier. The stratum corneum enables this barrier to prevent water loss from the skin and allowed amphibian / reptile ancestors to go onto the land. Overlapping scales and production of beta-keratins provide strong protection. Epidermal invagination led to the formation of avian feather and mammalian hair follicles in the dermis. Both adopted a proximal - distal growth mode which maintains endothermy. Feathers form hierarchical branches which produce the vane that makes flight possible. Recent discoveries of feathered dinosaurs in China inspire new thinking on the origin of feathers. In the laboratory, epithelial - mesenchymal recombinations and molecular mis-expressions were carried out to test the plasticity of epithelial organ formation. We review the work on the transformation of scales into feathers, conversion between barbs and rachis and the production of "chicken teeth". In mammals, tilting the balance of the BMP pathway in K14 noggin transgenic mice alters the number, size and phenotypes of different ectodermal organs, making investigators rethink the distinction between morpho-regulation and pathological changes. Models on the evolution of feathers and hairs from reptile integuments are discussed. A hypothetical Evo-Devo space where diverse integument appendages can be placed according to complex phenotypes and novel developmental mechanisms is presented.}, } @article {pmid15129242, year = {2004}, author = {Dalton, R}, title = {Feathered fossils cause a flap in museums.}, journal = {Nature}, volume = {429}, number = {6987}, pages = {5}, doi = {10.1038/429005a}, pmid = {15129242}, issn = {1476-4687}, mesh = {Animals ; Biological Evolution ; Birds/anatomy & histology ; China ; Dinosaurs/*anatomy & histology ; *Feathers ; *Fossils ; *Museums ; Paleontology/*legislation & jurisprudence ; }, } @article {pmid14676953, year = {2003}, author = {Lingham-Soliar, T}, title = {The dinosaurian origin of feathers: perspectives from dolphin (Cetacea) collagen fibers.}, journal = {Die Naturwissenschaften}, volume = {90}, number = {12}, pages = {563-567}, pmid = {14676953}, issn = {0028-1042}, mesh = {Adipose Tissue/chemistry ; Animals ; Birds/*anatomy & histology ; Cetacea/*physiology ; China ; Collagen/*analysis ; Dinosaurs/*anatomy & histology ; Feathers/*anatomy & histology ; Paleontology ; South Africa ; }, abstract = {The early origin of birds is a hotly disputed debate and may be broadly framed as a conflict between paleontologists and ornithologists. The paleontological emphasis has shifted from Archaeopteryx and its origins to recent finds of Cretaceous birds and "feathered" dinosaurs from China. The identification of alleged feathers has, however, relied principally on the visual image. Some workers have interpreted these integumentary structures as collagen fibers. To test the latter hypothesis, using light microscopy, collagen from the hypodermis (blubber) and subdermal connective tissue sheath was examined from a dolphin that had been buried for a year as part of an experiment. Within the blubber, toward the central thicker parts of the material, the collagen fibers had compacted and the three-dimensional latticework of normal blubber had more or less collapsed. Chromatographic analysis of the blubber revealed pronounced oxidation of the unsaturated lipids, probably accounting for the collapse of the latticework. Fibers normally bound together in bundles became separated into individual fibers or smaller bundles by degradation of the glue-like substance binding them together. These degraded collagen fibers show, in many instances, feather-like patterns, strikingly reminiscent of many of those identified as either "protofeathers" or "modern" feathers in dromaeosaurid dinosaurs. The findings throw serious doubt on the virtually complete reliance on visual image by supporters of the feathered dinosaur thesis and emphasize the need for more rigorous methods of identification using modern feathers as a frame of reference. Since collagen is the main fiber type found in most supporting tissues, the results have wide implications regarding the degradation and fossilization of vertebrate integument, such as that of the ichthyosaurs, dinosaurs and birds.}, } @article {pmid12955841, year = {2003}, author = {Sawyer, RH and Washington, LD and Salvatore, BA and Glenn, TC and Knapp, LW}, title = {Origin of archosaurian integumentary appendages: the bristles of the wild turkey beard express feather-type beta keratins.}, journal = {Journal of experimental zoology. Part B, Molecular and developmental evolution}, volume = {297}, number = {1}, pages = {27-34}, doi = {10.1002/jez.b.17}, pmid = {12955841}, issn = {1552-5007}, mesh = {Animals ; Blotting, Western ; Dinosaurs/*anatomy & histology ; Feathers ; Keratins/*genetics ; Microscopy, Electron, Scanning ; Skin/*ultrastructure ; Turkeys/*anatomy & histology/*genetics ; }, abstract = {The discovery that structurally unique "filamentous integumentary appendages" are associated with several different non-avian dinosaurs continues to stimulate the development of models to explain the evolutionary origin of feathers. Taking the phylogenetic relationships of the non-avian dinosaurs into consideration, some models propose that the "filamentous integumentary appendages" represent intermediate stages in the sequential evolution of feathers. Here we present observations on a unique integumentary structure, the bristle of the wild turkey beard, and suggest that this non-feather appendage provides another explanation for some of the "filamentous integumentary appendages." Unlike feathers, beard bristles grow continuously from finger-like outgrows of the integument lacking follicles. We find that these beard bristles, which show simple branching, are hollow, distally, and express the feather-type beta keratins. The significance of these observations to explanations for the evolution of archosaurian integumentary appendages is discussed.}, } @article {pmid12949769, year = {2003}, author = {Sawyer, RH and Knapp, LW}, title = {Avian skin development and the evolutionary origin of feathers.}, journal = {Journal of experimental zoology. Part B, Molecular and developmental evolution}, volume = {298}, number = {1}, pages = {57-72}, doi = {10.1002/jez.b.26}, pmid = {12949769}, issn = {1552-5007}, mesh = {Animals ; *Biological Evolution ; Birds/embryology/genetics/*physiology ; Dinosaurs/physiology ; Feathers/*anatomy & histology/embryology ; Integumentary System/physiology ; Keratins/genetics ; *Models, Biological ; Morphogenesis/physiology ; Skin/*embryology ; }, abstract = {The discovery of several dinosaurs with filamentous integumentary appendages of different morphologies has stimulated models for the evolutionary origin of feathers. In order to understand these models, knowledge of the development of the avian integument must be put into an evolutionary context. Thus, we present a review of avian scale and feather development, which summarizes the morphogenetic events involved, as well as the expression of the beta (beta) keratin multigene family that characterizes the epidermal appendages of reptiles and birds. First we review information on the evolution of the ectodermal epidermis and its beta (beta) keratins. Then we examine the morphogenesis of scutate scales and feathers including studies in which the extraembryonic ectoderm of the chorion is used to examine dermal induction. We also present studies on the scaleless (sc) mutant, and, because of the recent discovery of "four-winged" dinosaurs, we review earlier studies of a chicken strain, Silkie, that expresses ptilopody (pti), "feathered feet." We conclude that the ability of the ectodermal epidermis to generate discrete cell populations capable of forming functional structural elements consisting of specific members of the beta keratin multigene family was a plesiomorphic feature of the archosaurian ancestor of crocodilians and birds. Evidence suggests that the discrete epidermal lineages that make up the embryonic feather filament of extant birds are homologous with similar embryonic lineages of the developing scutate scales of birds and the scales of alligators. We believe that the early expression of conserved signaling modules in the embryonic skin of the avian ancestor led to the early morphogenesis of the embryonic feather filament, with its periderm, sheath, and barb ridge lineages forming the first protofeather. Invagination of the epidermis of the protofeather led to formation of the follicle providing for feather renewal and diversification. The observations that scale formation in birds involves an inhibition of feather formation coupled with observations on the feathered feet of the scaleless (High-line) and Silkie strains support the view that the ancestor of modern birds may have had feathered hind limbs similar to those recently discovered in nonavian dromaeosaurids. And finally, our recent observation on the bristles of the wild turkey beard raises the possibility that similar integumentary appendages may have adorned nonavian dinosaurs, and thus all filamentous integumentary appendages may not be homologous to modern feathers.}, } @article {pmid12949768, year = {2003}, author = {Chuong, CM and Wu, P and Zhang, FC and Xu, X and Yu, M and Widelitz, RB and Jiang, TX and Hou, L}, title = {Adaptation to the sky: Defining the feather with integument fossils from mesozoic China and experimental evidence from molecular laboratories.}, journal = {Journal of experimental zoology. Part B, Molecular and developmental evolution}, volume = {298}, number = {1}, pages = {42-56}, pmid = {12949768}, issn = {1552-5007}, support = {R01 AR042177-07S1/AR/NIAMS NIH HHS/United States ; R01 CA083716/CA/NCI NIH HHS/United States ; R21CA09432/CA/NCI NIH HHS/United States ; R01 AR047364-01A2/AR/NIAMS NIH HHS/United States ; R01 AR042177/AR/NIAMS NIH HHS/United States ; R01 AR047364/AR/NIAMS NIH HHS/United States ; R01 AR042177-08S1/AR/NIAMS NIH HHS/United States ; R01AR42177/AR/NIAMS NIH HHS/United States ; R01 AR042177-08/AR/NIAMS NIH HHS/United States ; R01CA83716/CA/NCI NIH HHS/United States ; R01 AR042177-07/AR/NIAMS NIH HHS/United States ; }, mesh = {Adaptation, Biological ; Animals ; *Biological Evolution ; Birds/anatomy & histology/*physiology ; Chick Embryo ; China ; Dinosaurs/physiology ; Feathers/*anatomy & histology/embryology ; Flight, Animal/physiology ; *Fossils ; Integumentary System/physiology ; Models, Animal ; *Models, Biological ; }, abstract = {In this special issue on the Evo-Devo of amniote integuments, Alibardi has discussed the adaptation of the integument to the land. Here we will discuss the adaptation to the sky. We first review a series of fossil discoveries representing intermediate forms of feathers or feather-like appendages from dinosaurs and Mesozoic birds from the Jehol Biota of China. We then discuss the molecular and developmental biological experiments using chicken integuments as the model. Feather forms can be modulated using retrovirus mediated gene mis-expression that mimics those found in nature today and in the evolutionary past. The molecular conversions among different types of integument appendages (feather, scale, tooth) are discussed. From this evidence, we recognize that not all organisms with feathers are birds, and that not all skin appendages with hierarchical branches are feathers. We develop a set of criteria for true avian feathers: 1) possessing actively proliferating cells in the proximal follicle for proximo-distal growth mode; 2) forming hierarchical branches of rachis, barbs, and barbules, with barbs formed by differential cell death and bilaterally or radially symmetric; 3) having a follicle structure, with mesenchyme core during development; 4) when mature, consisting of epithelia without mesenchyme core and with two sides of the vane facing the previous basal and supra-basal layers, respectively; and 5) having stem cells and dermal papilla in the follicle and hence the ability to molt and regenerate. A model of feather evolution from feather bud --> barbs --> barbules --> rachis is presented, which is opposite to the old view of scale plate --> rachis --> barbs --> barbules (Regal, '75; Q Rev Biol 50:35).}, } @article {pmid21680458, year = {2003}, author = {Chang, BS}, title = {Ancestral gene reconstruction and synthesis of ancient rhodopsins in the laboratory.}, journal = {Integrative and comparative biology}, volume = {43}, number = {4}, pages = {500-507}, doi = {10.1093/icb/43.4.500}, pmid = {21680458}, issn = {1540-7063}, abstract = {Laboratory synthesis of ancestral proteins offers an intriguing opportunity to study the past directly. The development of Bayesian methods to infer ancestral sequences, combined with advances in models of molecular evolution, and synthetic gene technology make this an increasingly promising approach in evolutionary studies of molecular function. Visual pigments form the first step in the biochemical cascade of events in the retina in all animals known to possess visual capabilities. In vertebrates, the necessity of spanning a dynamic range of light intensities of many orders of magnitude has given rise to two different types of photoreceptors, rods specialized for dim-light conditions, and cones for daylight and color vision. These photoreceptors contain different types of visual pigment genes. Reviewed here are methods of inferring ancestral sequences, chemical synthesis of artificial ancestral genes in the laboratory, and applications to the evolution of vertebrate visual systems and the experimental recreation of an archosaur rod visual pigment. The ancestral archosaurs gave rise to several notable lineages of diapsid reptiles, including the birds and the dinosaurs, and would have existed over 200 MYA. What little is known of their physiology comes from fossil remains, and inference based on the biology of their living descendants. Despite its age, an ancestral archosaur pigment was successfully recreated in the lab, and showed interesting properties of its wavelength sensitivity that may have implications for the visual capabilities of the ancestral archosaurs in dim light.}, } @article {pmid12616863, year = {2003}, author = {Prum, OR and Brush, AH}, title = {Which came first, the feather or the bird?.}, journal = {Scientific American}, volume = {288}, number = {3}, pages = {84-93}, doi = {10.1038/scientificamerican0303-84}, pmid = {12616863}, issn = {0036-8733}, mesh = {Animals ; *Biological Evolution ; Birds ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins/genetics/physiology ; Cell Differentiation ; Dinosaurs ; *Feathers/cytology/growth & development ; Fossils ; Hedgehog Proteins ; Trans-Activators/genetics/physiology ; *Transforming Growth Factor beta ; }, } @article {pmid12594504, year = {2003}, author = {Zhou, Z and Barrett, PM and Hilton, J}, title = {An exceptionally preserved Lower Cretaceous ecosystem.}, journal = {Nature}, volume = {421}, number = {6925}, pages = {807-814}, doi = {10.1038/nature01420}, pmid = {12594504}, issn = {0028-0836}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/classification/physiology ; China ; Dinosaurs/anatomy & histology/classification/physiology ; *Ecosystem ; *Fossils ; Invertebrates/anatomy & histology/classification/physiology ; Phylogeny ; Plants ; }, abstract = {Fieldwork in the Early Cretaceous Jehol Group, northeastern China has revealed a plethora of extraordinarily well-preserved fossils that are shaping some of the most contentious debates in palaeontology and evolutionary biology. These discoveries include feathered theropod dinosaurs and early birds, which provide additional, indisputable support for the dinosaurian ancestry of birds, and much new evidence on the evolution of feathers and flight. Specimens of putative basal angiosperms and primitive mammals are clarifying details of the early radiations of these major clades. Detailed soft-tissue preservation of the organisms from the Jehol Biota is providing palaeobiological insights that would not normally be accessible from the fossil record.}, } @article {pmid12543943, year = {2003}, author = {Stokstad, E}, title = {Paleontology. Four-winged dinos create a flutter.}, journal = {Science (New York, N.Y.)}, volume = {299}, number = {5606}, pages = {491}, doi = {10.1126/science.299.5606.491a}, pmid = {12543943}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Biomechanical Phenomena ; Birds/anatomy & histology/physiology ; China ; *Dinosaurs/anatomy & histology/physiology ; *Feathers ; *Flight, Animal ; Forelimb/anatomy & histology ; *Fossils ; Hindlimb/anatomy & histology ; Locomotion ; }, } @article {pmid12540892, year = {2003}, author = {Xu, X and Zhou, Z and Wang, X and Kuang, X and Zhang, F and Du, X}, title = {Four-winged dinosaurs from China.}, journal = {Nature}, volume = {421}, number = {6921}, pages = {335-340}, doi = {10.1038/nature01342}, pmid = {12540892}, issn = {0028-0836}, mesh = {Animals ; *Biological Evolution ; Birds/*anatomy & histology/classification/physiology ; China ; Dinosaurs/*anatomy & histology/classification/physiology ; Feathers/anatomy & histology/physiology ; *Flight, Animal ; *Fossils ; Models, Biological ; Wings, Animal/*anatomy & histology/physiology ; }, abstract = {Although the dinosaurian hypothesis of bird origins is widely accepted, debate remains about how the ancestor of birds first learned to fly. Here we provide new evidence suggesting that basal dromaeosaurid dinosaurs were four-winged animals and probably could glide, representing an intermediate stage towards the active, flapping-flight stage. The new discovery conforms to the predictions of early hypotheses that proavians passed through a tetrapteryx stage.}, } @article {pmid12540882, year = {2003}, author = {Prum, RO}, title = {Palaeontology: Dinosaurs take to the air.}, journal = {Nature}, volume = {421}, number = {6921}, pages = {323-324}, doi = {10.1038/421323a}, pmid = {12540882}, issn = {0028-0836}, mesh = {Animals ; Biological Evolution ; Birds/*anatomy & histology/*physiology ; China ; Dinosaurs/*anatomy & histology/*physiology ; Feathers/anatomy & histology/physiology ; *Flight, Animal ; *Fossils ; Models, Biological ; Wings, Animal/*anatomy & histology/*physiology ; }, } @article {pmid12532020, year = {2003}, author = {Dial, KP}, title = {Wing-assisted incline running and the evolution of flight.}, journal = {Science (New York, N.Y.)}, volume = {299}, number = {5605}, pages = {402-404}, doi = {10.1126/science.1078237}, pmid = {12532020}, issn = {1095-9203}, mesh = {Acceleration ; Animals ; *Biological Evolution ; Biomechanical Phenomena ; Birds/anatomy & histology/growth & development/*physiology ; Feathers/physiology ; *Flight, Animal ; Forelimb/physiology ; Hindlimb/physiology ; *Locomotion ; Movement ; Running ; Wings, Animal/*physiology ; }, abstract = {Flapping wings of galliform birds are routinely used to produce aerodynamic forces oriented toward the substrate to enhance hindlimb traction. Here, I document this behavior in natural and laboratory settings. Adult birds fully capable of aerial flight preferentially employ wing-assisted incline running (WAIR), rather than flying, to reach elevated refuges (such as cliffs, trees, and boulders). From the day of hatching and before attaining sustained aerial flight, developing ground birds use WAIR to enhance their locomotor performance through improved foot traction, ultimately permitting vertical running. WAIR provides insight from behaviors observable in living birds into the possible role of incipient wings in feathered theropod dinosaurs and offers a previously unstudied explanation for the evolution of avian flight.}, } @article {pmid12531990, year = {2003}, author = {Pennisi, E}, title = {Evolutionary biology. Uphill dash may have led to flight.}, journal = {Science (New York, N.Y.)}, volume = {299}, number = {5605}, pages = {329}, doi = {10.1126/science.299.5605.329}, pmid = {12531990}, issn = {1095-9203}, mesh = {Animals ; *Biological Evolution ; Biomechanical Phenomena ; Birds/anatomy & histology/growth & development/*physiology ; Dinosaurs/anatomy & histology/physiology ; Feathers/physiology ; *Flight, Animal ; Fossils ; *Locomotion ; Movement ; Running ; Walking ; Wings, Animal/*physiology ; }, } @article {pmid12442169, year = {2002}, author = {Yu, M and Wu, P and Widelitz, RB and Chuong, CM}, title = {The morphogenesis of feathers.}, journal = {Nature}, volume = {420}, number = {6913}, pages = {308-312}, pmid = {12442169}, issn = {0028-0836}, support = {R01 AR042177-07S1/AR/NIAMS NIH HHS/United States ; R01 AR042177-05/AR/NIAMS NIH HHS/United States ; R01 AR042177/AR/NIAMS NIH HHS/United States ; R01 AR042177-06/AR/NIAMS NIH HHS/United States ; R01 AR042177-06S1/AR/NIAMS NIH HHS/United States ; R01 AR042177-07/AR/NIAMS NIH HHS/United States ; }, mesh = {Animals ; Apoptosis ; Avian Sarcoma Viruses/genetics ; Biological Evolution ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Protein 4 ; Bone Morphogenetic Proteins/genetics/metabolism ; Carrier Proteins ; Chick Embryo/*embryology ; Epithelium/anatomy & histology/embryology ; Feathers/anatomy & histology/*embryology ; Gene Expression Regulation, Developmental ; Hedgehog Proteins ; In Situ Hybridization ; Models, Biological ; Morphogenesis ; Phenotype ; Proteins/genetics/metabolism ; RNA, Messenger/genetics/metabolism ; Trans-Activators/metabolism ; *Transforming Growth Factor beta ; Transgenes/genetics ; }, abstract = {Feathers are highly ordered, hierarchical branched structures that confer birds with the ability of flight. Discoveries of fossilized dinosaurs in China bearing 'feather-like' structures have prompted interest in the origin and evolution of feathers. However, there is uncertainty about whether the irregularly branched integumentary fibres on dinosaurs such as Sinornithosaurus are truly feathers, and whether an integumentary appendage with a major central shaft and notched edges is a non-avian feather or a proto-feather. Here, we use a developmental approach to analyse molecular mechanisms in feather-branching morphogenesis. We have used the replication-competent avian sarcoma retrovirus to deliver exogenous genes to regenerating flight feather follicles of chickens. We show that the antagonistic balance between noggin and bone morphogenetic protein 4 (BMP4) has a critical role in feather branching, with BMP4 promoting rachis formation and barb fusion, and noggin enhancing rachis and barb branching. Furthermore, we show that sonic hedgehog (Shh) is essential for inducing apoptosis of the marginal plate epithelia, which results in spaces between barbs. Our analyses identify the molecular pathways underlying the topological transformation of feathers from cylindrical epithelia to the hierarchical branched structures, and provide insights on the possible developmental mechanisms in the evolution of feather forms.}, } @article {pmid12365352, year = {2002}, author = {Prum, RO and Brush, AH}, title = {The evolutionary origin and diversification of feathers.}, journal = {The Quarterly review of biology}, volume = {77}, number = {3}, pages = {261-295}, doi = {10.1086/341993}, pmid = {12365352}, issn = {0033-5770}, mesh = {*Adaptation, Physiological ; Animals ; *Biological Evolution ; *Birds ; *Dinosaurs ; Feathers/*anatomy & histology/growth & development/physiology ; Hair Follicle/growth & development ; Keratins/physiology ; *Models, Theoretical ; }, abstract = {Progress on the evolutionary origin and diversification of feathers has been hampered by conceptual problems and by the lack of plesiomorphic feather fossils. Recently, both of these limitations have been overcome by the proposal of the developmental theory of the origin of feathers, and the discovery of primitive feather fossils on nonavian theropod dinosaurs. The conceptual problems of previous theories of the origin of feathers are reviewed, and the alternative developmental theory is presented and discussed. The developmental theory proposes that feathers evolved through a series of evolutionary novelties in developmental mechanisms of the follicle and feather germ. The discovery of primitive and derived fossil feathers on a diversity of coelurosaurian theropod dinosaurs documents that feathers evolved and diversified in nonavian theropods before the origin of birds and before the origin of flight. The morphologies of these primitive feathers are congruent with the predictions of the developmental theory. Alternatives to the theropod origin of feathers are critique and rejected. Hypotheses for the initial function of feathers are reviewed. The aerodynamic theory of feather origins is falsified, but many other functions remain developmentally and phylogenetically plausible. Whatever their function, feathers evolved by selection for a follicle that would grow an emergent tubular appendage. Feathers are inherently tubular structures. The homology of feathers and scales is weakly supported. Feathers are composed of a suite of evolutionary novelties that evolved by the duplication, hierarchical organization, interaction, dissociation, and differentiation of morphological modules. The unique capacity for modular subdivision of the tubular feather follicle and germ has fostered the evolution of numerous innovations that characterize feathers. The evolution of feather keratin and the molecular basis of feather development are also discussed.}, } @article {pmid12216277, year = {2002}, author = {Sanz, JL and Ortega, F}, title = {The birds from Las Hoyas.}, journal = {Science progress}, volume = {85}, number = {Pt 2}, pages = {113-130}, doi = {10.3184/003685002783238843}, pmid = {12216277}, issn = {0036-8504}, mesh = {Animals ; *Biological Evolution ; Biomechanical Phenomena ; *Birds/anatomy & histology/classification/physiology ; Flight, Animal/physiology ; Fossils ; Spain ; Wings, Animal/anatomy & histology/physiology ; }, abstract = {Information on the first steps of the avian evolutionary history has dramatically increased during the last few years. The fossil record provides a general view of the morphological changes of the avian flight apparatus from nonvolant ancestors (non-avian theropod dinosaurs) to the first derived fliers of the Early Cretaceous. The Las Hoyas bird record includes three genera: Iberomesornis, Concornis and Eoalulavis. This fossil material has yielded information about the early avian evolutionary history. These Early Cretaceous birds (some 120 Myr old) had a wingbeat cycle and breathing devices similar to those of extant birds. The function of the rectricial fan was also similar. In the evolutionary transition from cursorial ancestors to derived fliers it is possible to verify a trend to increase lift. Primitive wing aspect ratio morphotypes were elliptical ones, other derived morphotypes appeared, for example, in the Neornithes (extant birds). Some primitive fliers, like the Las Hoyas genus Eoalulavis, had an alula (feathers attached to the first digit of the hand) similar to that of present day birds, indicating braking and manoeuvring skills similar to those of their extant relatives. Primitive avian life habits are poorly understood. Some evidence from the Las Hoyas bird record indicates that Early Cretaceous birds were present in the trophic chains.}, } @article {pmid12200476, year = {2002}, author = {Chang, BS and Jönsson, K and Kazmi, MA and Donoghue, MJ and Sakmar, TP}, title = {Recreating a functional ancestral archosaur visual pigment.}, journal = {Molecular biology and evolution}, volume = {19}, number = {9}, pages = {1483-1489}, doi = {10.1093/oxfordjournals.molbev.a004211}, pmid = {12200476}, issn = {0737-4038}, mesh = {Amino Acid Sequence ; Animals ; Base Sequence ; Cattle ; Cell Line ; Codon/genetics ; Dinosaurs/*genetics ; *Evolution, Molecular ; Likelihood Functions ; Molecular Sequence Data ; Phylogeny ; Protein Binding ; Protein Conformation ; Reptiles/*genetics ; Retinaldehyde/metabolism ; Rhodopsin/*chemistry/*genetics/metabolism ; Spectrophotometry, Ultraviolet ; Transducin/metabolism ; }, abstract = {The ancestors of the archosaurs, a major branch of the diapsid reptiles, originated more than 240 MYA near the dawn of the Triassic Period. We used maximum likelihood phylogenetic ancestral reconstruction methods and explored different models of evolution for inferring the amino acid sequence of a putative ancestral archosaur visual pigment. Three different types of maximum likelihood models were used: nucleotide-based, amino acid-based, and codon-based models. Where possible, within each type of model, likelihood ratio tests were used to determine which model best fit the data. Ancestral reconstructions of the ancestral archosaur node using the best-fitting models of each type were found to be in agreement, except for three amino acid residues at which one reconstruction differed from the other two. To determine if these ancestral pigments would be functionally active, the corresponding genes were chemically synthesized and then expressed in a mammalian cell line in tissue culture. The expressed artificial genes were all found to bind to 11-cis-retinal to yield stable photoactive pigments with lambda(max) values of about 508 nm, which is slightly redshifted relative to that of extant vertebrate pigments. The ancestral archosaur pigments also activated the retinal G protein transducin, as measured in a fluorescence assay. Our results show that ancestral genes from ancient organisms can be reconstructed de novo and tested for function using a combination of phylogenetic and biochemical methods.}, } @article {pmid12140555, year = {2002}, author = {Zhou, Z and Zhang, F}, title = {A long-tailed, seed-eating bird from the Early Cretaceous of China.}, journal = {Nature}, volume = {418}, number = {6896}, pages = {405-409}, doi = {10.1038/nature00930}, pmid = {12140555}, issn = {0028-0836}, mesh = {Adaptation, Physiological ; Animals ; *Biological Evolution ; Birds/*anatomy & histology/classification/*physiology ; China ; *Diet ; *Fossils ; Phylogeny ; *Seeds ; Skeleton ; }, abstract = {The lacustrine deposits of the Yixian and Jiufotang Formations in the Early Cretaceous Jehol Group in the western Liaoning area of northeast China are well known for preserving feathered dinosaurs, primitive birds and mammals. Here we report a large basal bird, Jeholornis prima gen. et sp. nov., from the Jiufotang Formation. This bird is distinctively different from other known birds of the Early Cretaceous period in retaining a long skeletal tail with unexpected elongated prezygopophyses and chevrons, resembling that of dromaeosaurids, providing a further link between birds and non-avian theropods. Despite its basal position in early avian evolution, the advanced features of the pectoral girdle and the carpal trochlea of the carpometacarpus of Jeholornis indicate the capability of powerful flight. The dozens of beautifully preserved ovules of unknown plant taxa in the stomach represents direct evidence for seed-eating adaptation in birds of the Mesozoic era.}, } @article {pmid12008971, year = {2002}, author = {Zhou, Z and Zhang, F}, title = {Largest bird from the Early Cretaceous and its implications for the earliest avian ecological diversification.}, journal = {Die Naturwissenschaften}, volume = {89}, number = {1}, pages = {34-38}, doi = {10.1007/s00114-001-0276-9}, pmid = {12008971}, issn = {0028-1042}, mesh = {Animals ; Birds/*anatomy & histology/*classification ; China ; Ecosystem ; Paleontology ; Phylogeny ; }, abstract = {With only one known exception, early Cretaceous birds were smaller than their closest theropod dinosaur relatives. Here we report on a new bird from the Early Cretaceous feathered-dinosaur-bearing continental deposits of Liaoning, northeast China, which is not only larger than Archaeopteryx but is nearly twice as large as the basal dromaeosaur Microraptor. The new taxon, Sapeornis chaoyangensis gen. et sp. nov., has a more basal phylogenetic position than all other birds except for Archaeopteryx. Its exceptionally long forelimbs, well-developed deltoid crest of the humerus, proximally fused metacarpals, relatively short hindlimbs and short pygo-style indicate powerful soaring capability and further suggest that by the Early Cretaceous ecological diversification of early birds was greater than previously assumed. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00114-001-0276-9.}, } @article {pmid11882883, year = {2002}, author = {Norell, M and Ji, Q and Gao, K and Yuan, C and Zhao, Y and Wang, L}, title = {Palaeontology: 'modern' feathers on a non-avian dinosaur.}, journal = {Nature}, volume = {416}, number = {6876}, pages = {36-37}, doi = {10.1038/416036a}, pmid = {11882883}, issn = {0028-0836}, mesh = {Animals ; Biological Evolution ; China ; *Dinosaurs/anatomy & histology ; *Feathers ; *Fossils ; }, abstract = {Discoveries of integumentary coverings on non-avian theropod dinosaurs are becoming commonplace. But the only definitive evidence so far that any of these animals had feathers as we know them today has come from the oviraptorosaur Caudipteryx and the enigmatic coleurosaur Protarchaeopteryx, both of which are considered by some to be secondarily flightless birds. Here we describe the occurrence of pinnate feathers, which clearly feature a rachis and barbs, on a small, non-avian dromaeosaur from northern China. This finding indicates that feathers of modern aspect evolved in dinosaurs before the emergence of birds and flight.}, } @article {pmid11399531, year = {2001}, author = {Chuong, CM and Hou, L and Chen, PJ and Wu, P and Patel, N and Chen, Y}, title = {Dinosaur's feather and chicken's tooth? Tissue engineering of the integument.}, journal = {European journal of dermatology : EJD}, volume = {11}, number = {4}, pages = {286-292}, pmid = {11399531}, issn = {1167-1122}, support = {R01 AR042177-07S1/AR/NIAMS NIH HHS/United States ; R01 AR042177/AR/NIAMS NIH HHS/United States ; R01 AR042177-06/AR/NIAMS NIH HHS/United States ; R01 AR042177-06S1/AR/NIAMS NIH HHS/United States ; R01 AR042177-07/AR/NIAMS NIH HHS/United States ; }, mesh = {Animals ; Biomedical Engineering ; Chickens ; Feathers/*embryology ; Humans ; Skin/*growth & development ; Tooth/*embryology ; }, abstract = {The integument forms the interface between animals and the environment. During evolution, diverse integument and integument appendages have evolved to adapt animals to different niches. The formation of these different integument forms is based on the acquisition of novel developmental mechanisms. This is the way Nature does her tissue/organ engineering and experiments. To do tissue engineering of the integument in the new century for medical applications, we need to learn more principles from developmental and evolutionary studies. A novel diagram showing the evolution and development of integument complexity is presented, and the molecular pathways involved discussed. We then discuss two examples in which the gain and loss of appendages are modulated: transformation of avian scale epidermis into feathers with mutated beta catenin, and induction of chicken tooth like appendages with FGF, BMP and feather mesenchyme.}, } @article {pmid11323669, year = {2001}, author = {Ji, Q and Norell, MA and Gao, KQ and Ji, SA and Ren, D}, title = {The distribution of integumentary structures in a feathered dinosaur.}, journal = {Nature}, volume = {410}, number = {6832}, pages = {1084-1088}, doi = {10.1038/35074079}, pmid = {11323669}, issn = {0028-0836}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology ; Bone and Bones ; China ; *Feathers ; *Fossils ; *Reptiles/anatomy & histology/classification ; }, abstract = {Non-avian theropod dinosaurs with preserved integumentary coverings are becoming more common; but apart from the multiple specimens of Caudipteryx, which have true feathers, animals that are reasonably complete and entirely articulated that show these structures in relation to the body have not been reported. Here we report on an enigmatic small theropod dinosaur that is covered with filamentous feather-like structures over its entire body.}, } @article {pmid11242078, year = {2001}, author = {Xu, X and Zhou, Z and Prum, RO}, title = {Branched integumental structures in Sinornithosaurus and the origin of feathers.}, journal = {Nature}, volume = {410}, number = {6825}, pages = {200-204}, doi = {10.1038/35065589}, pmid = {11242078}, issn = {0028-0836}, mesh = {Animals ; *Biological Evolution ; *Birds ; *Feathers ; *Fossils ; *Reptiles ; }, abstract = {The evolutionary origin of feathers has long been obscured because no morphological antecedents were known to the earliest, structurally modern feathers of Archaeopteryx. It has been proposed that the filamentous integumental appendages on several theropod dinosaurs are primitive feathers; but the homology between these filamentous structures and feathers has been disputed, and two taxa with true feathers (Caudipteryx and Protarchaeopteryx) have been proposed to be flightless birds. Confirmation of the theropod origin of feathers requires documentation of unambiguously feather-like structures in a clearly non-avian theropod. Here we describe our observations of the filamentous integumental appendages of the basal dromaeosaurid dinosaur Sinornithosaurus millenii, which indicate that they are compound structures composed of multiple filaments. Furthermore, these appendages exhibit two types of branching structure that are unique to avian feathers: filaments joined in a basal tuft, and filaments joined at their bases in series along a central filament. Combined with the independent phylogenetic evidence supporting the theropod ancestry of birds, these observations strongly corroborate the hypothesis that the integumental appendages of Sinornithosaurus are homologous with avian feathers. The plesiomorphic feathers of Sinornithosaurus also conform to the predictions of an independent, developmental model of the evolutionary origin of feathers.}, } @article {pmid11187036, year = {2000}, author = {Stokstad, E}, title = {Paleontology. Tiny, feathered dino is most birdlike yet.}, journal = {Science (New York, N.Y.)}, volume = {290}, number = {5498}, pages = {1871-1872}, doi = {10.1126/science.290.5498.1871a}, pmid = {11187036}, issn = {0036-8075}, mesh = {Animals ; Biological Evolution ; *Birds/anatomy & histology/physiology ; China ; Feathers/anatomy & histology ; Foot/anatomy & histology ; *Fossils ; Locomotion ; *Reptiles/anatomy & histology/physiology ; Tail/anatomy & histology ; }, abstract = {Chinese paleontologists studying the fossil known as Microraptor describe it as both the smallest and the most birdlike dinosaur yet discovered. In this week's issue of Nature, they say the crow-sized, feathered creature--whose fossilized tail once formed part of a now-discredited "missing link" between birds and dinosaurs known as Archaeoraptor--belongs to the dromaeosaurs, dinosaurs that many paleontologists consider the closest dinosaurian relatives of birds.}, } @article {pmid10896578, year = {2000}, author = {Stokstad, E}, title = {Paleontology. Feathers, or flight of fancy?.}, journal = {Science (New York, N.Y.)}, volume = {288}, number = {5474}, pages = {2124-2125}, doi = {10.1126/science.288.5474.2124}, pmid = {10896578}, issn = {0036-8075}, mesh = {Animals ; *Biological Evolution ; *Birds/anatomy & histology ; *Feathers/anatomy & histology ; *Fossils ; Reptiles/*anatomy & histology ; }, abstract = {On page 2202, researchers describe the 220-million-year-old Longisquama insignis, a squat, mouse-sized reptile with at least six vanelike appendages up to 12 centimeters long sprouting from its spine. The authors argue that the appendages are feathers much like those of modern birds; outside the paper, they have touted the fossil as "an ideal bird ancestor." That conclusion has infuriated paleontologists--not just because it challenges the prevalent theory that birds evolved from theropod dinosaurs, but because they say it does so in an unscientific way.}, } @article {pmid10877683, year = {2000}, author = {Normile, D}, title = {Paleontology. New feathered dino firms up bird links.}, journal = {Science (New York, N.Y.)}, volume = {288}, number = {5472}, pages = {1721}, doi = {10.1126/science.288.5472.1721}, pmid = {10877683}, issn = {0036-8075}, mesh = {Animals ; Biological Evolution ; *Birds/anatomy & histology ; Bone and Bones/anatomy & histology ; China ; *Feathers ; *Fossils ; *Reptiles/anatomy & histology ; }, abstract = {Last week, Chinese scientists presented evidence from a new specimen dug up in Liaoning Province that they say strengthens the case for the bird-dinosaur link. The finding, one of several fossils displayed at a meeting here, is the third known specimen of a strange creature known as Caudipteryx which, unlike any other known dinosaur fossil, shows the unmistakable imprints of feathers. The researcher who described the new specimen at the meeting has identified 16 characteristics of the new fossil that are more similar to dinosaurs than to early birds, reinforcing the views of most Western scientists.}, } @article {pmid10578107, year = {1999}, author = {Prum, RO}, title = {Development and evolutionary origin of feathers.}, journal = {The Journal of experimental zoology}, volume = {285}, number = {4}, pages = {291-306}, pmid = {10578107}, issn = {0022-104X}, mesh = {Animals ; *Biological Evolution ; Birds ; Cell Differentiation ; Feathers/*anatomy & histology ; Fossils ; Models, Biological ; Reptiles/anatomy & histology ; Skin/anatomy & histology ; }, abstract = {Avian feathers are a complex evolutionary novelty characterized by structural diversity and hierarchical development. Here, I propose a functionally neutral model of the origin and evolutionary diversification of bird feathers based on the hierarchical details of feather development. I propose that feathers originated with the evolution of the first feather follicle-a cylindrical epidermal invagination around the base of a dermal papilla. A transition series of follicle and feather morphologies is hypothesized to have evolved through a series of stages of increasing complexity in follicle structure and follicular developmental mechanisms. Follicular evolution proceeded with the origin of the undifferentiated collar (stage I), barb ridges (stage II), helical displacement of barb ridges, barbule plates, and the new barb locus (stage III), differentiation of pennulae of distal and proximal barbules (stage IV), and diversification of barbule structure and the new barb locus position (stage V). The model predicts that the first feather was an undifferentiated cylinder (stage I), which was followed by a tuft of unbranched barbs (stage II). Subsequently, with the origin of the rachis and barbules, the bipinnate feather evolved (stage III), followed then by the pennaceous feather with a closed vane (stage IV) and other structural diversity (stages Va-f). The model is used to evaluate the developmental plausibility of proposed functional theories of the origin of feathers. Early feathers (stages I, II) could have functioned in communication, defense, thermal insulation, or water repellency. Feathers could not have had an aerodynamic function until after bipinnate, closed pennaceous feathers (stage IV) had evolved. The morphology of the integumental structures of the coelurisaurian theropod dinosaurs Sinosauropteryx and Beipiaosaurus are congruent with the model's predictions of the form of early feathers (stage I or II). Additional research is required to examine whether these fossil integumental structures developed from follicles and are homologous with avian feathers. J. Exp. Zool. (Mol. Dev. Evol.) 285:291-306, 1999.}, } @article {pmid10381873, year = {1999}, author = {Sereno, PC}, title = {The evolution of dinosaurs.}, journal = {Science (New York, N.Y.)}, volume = {284}, number = {5423}, pages = {2137-2147}, doi = {10.1126/science.284.5423.2137}, pmid = {10381873}, issn = {0036-8075}, mesh = {Animals ; *Biological Evolution ; Birds/anatomy & histology/physiology ; Body Constitution ; Feathers ; Flight, Animal ; Fossils ; Locomotion ; *Paleontology ; Phylogeny ; *Reptiles/anatomy & histology/physiology ; }, abstract = {The ascendancy of dinosaurs on land near the close of the Triassic now appears to have been as accidental and opportunistic as their demise and replacement by therian mammals at the end of the Cretaceous. The dinosaurian radiation, launched by 1-meter-long bipeds, was slower in tempo and more restricted in adaptive scope than that of therian mammals. A notable exception was the evolution of birds from small-bodied predatory dinosaurs, which involved a dramatic decrease in body size. Recurring phylogenetic trends among dinosaurs include, to the contrary, increase in body size. There is no evidence for co-evolution between predators and prey or between herbivores and flowering plants. As the major land masses drifted apart, dinosaurian biogeography was molded more by regional extinction and intercontinental dispersal than by the breakup sequence of Pangaea.}, } @article {pmid28565606, year = {1996}, author = {Gatesy, SM and Dial, KP}, title = {FROM FROND TO FAN: ARCHAEOPTERYX AND THE EVOLUTION OF SHORT-TAILED BIRDS.}, journal = {Evolution; international journal of organic evolution}, volume = {50}, number = {5}, pages = {2037-2048}, doi = {10.1111/j.1558-5646.1996.tb03590.x}, pmid = {28565606}, issn = {1558-5646}, abstract = {Modern birds have extremely short tail skeletons relative to Archaeopteryx and nonavialian theropod dinosaurs. Long- and short-tailed birds also differ in the conformation of main tail feathers making up the flight surface: frond shaped in Archaeopteryx and fan shaped in extant fliers. Mechanisms of tail fanning were evaluated by electromyography in freely flying pigeons and turkeys and by electrical stimulation of caudal muscles in anesthetized birds. Results from these experiments reveal that the pygostyle, rectrices, rectricial bulbs, and bulbi rectricium musculature form a specialized fanning mechanism. Contrary to previous models, our data support the interpretation that the bulbi rectricium independently controls tail fanning; other muscles are neither capable of nor necessary for significant rectricial abduction. This bulb mechanism permits rapid changes in tail span, thereby allowing the exploitation of a wide range of lift forces. Isolation of the bulbs on the pygostyle effectively decouples tail fanning from fan movement, which is governed by the remaining caudal muscles. The tail of Archaeopteryx, however, differs from this arrangement in several important respects. Archaeopteryx probably had a limited range of lift forces and tight coupling between vertebral and rectricial movement. This would have made the tail of this primitive flier better suited to stabilization than maneuverability. The capacity to significantly alter lift and manipulate the flight surface without distortion may have been two factors favoring tail shortening and pygostyle development during avian evolution.}, } @article {pmid17809342, year = {1993}, author = {Feduccia, A}, title = {Evidence from claw geometry indicating arboreal habits of archaeopteryx.}, journal = {Science (New York, N.Y.)}, volume = {259}, number = {5096}, pages = {790-793}, doi = {10.1126/science.259.5096.790}, pmid = {17809342}, issn = {0036-8075}, abstract = {The Late Jurassic Archaeopteryx has been thought to have been a feathered predator adapted to running that represented a terrestrial stage in the evolution of true birds from coelurosaurian dinosaurs. Examination of claw geometry, however, shows that (i) modern ground- and tree-dwelling birds can be distinguished on the basis of claw curvature, in that greater claw arcs characterize tree-dwellers and trunk-climbers, and (ii) the claws of the pes (hind foot) and manus (front hand) of Archaeopteryx exhibit degrees of curvature typical of perching and trunk-climbing birds, respectively. On this basis, Archaeopteryx appears to have been a perching bird, not a cursorial predator.}, } @article {pmid17819218, year = {1986}, author = {Marshall, E}, title = {Dinosaurs ruffle some feathers in california.}, journal = {Science (New York, N.Y.)}, volume = {231}, number = {4733}, pages = {18-19}, doi = {10.1126/science.231.4733.18-b}, pmid = {17819218}, issn = {0036-8075}, }