Feduccia A.,University of North Carolina at Chapel Hill |
Czerkas S.A.,The Dinosaur Museum
Journal of Ornithology | Year: 2015
Considerable debate surrounds the numerous avian-like traits in core maniraptorans (oviraptorosaurs, troodontids, and dromaeosaurs), especially in the Chinese Early Cretaceous oviraptorosaur Caudipteryx, which preserves modern avian pennaceous primary remiges attached to the manus, as is the case in modern birds. Was Caudipteryx derived from earth-bound theropod dinosaurs, which is the predominant view among palaeontologists, or was it secondarily flightless, with volant avians or theropods as ancestors (the neoflightless hypothesis), which is another popular, but minority view. The discovery here of an aerodynamic propatagium in several specimens provides new evidence that Caudipteryx (and hence oviraptorosaurs) represent secondarily derived flightless ground dwellers, whether of theropod or avian affinity, and that their presence and radiation during the Cretaceous may have been a factor in the apparent scarcity of many other large flightless birds during that period. © Dt. Ornithologen-Gesellschaft e.V. 2015.
Czerkas S.A.,The Dinosaur Museum |
Feduccia A.,University of North Carolina at Chapel Hill
Journal of Ornithology | Year: 2014
Re-examination utilizing Keyence 3D digital microscopy and low angled illumination of the fossil Scansoriopteryx, a problematic sparrow-size pre-Archae-opteryx specimen from the Jurassic Daohugou Biotas, provides new evidence which challenges the widely accepted hypothesis that birds are derived from dinosaurs in which avian flight originated from cursorial forms. Contrary to previous interpretations in which Scansoriopteryx was con-sideredtobe a coelurosaurian theropod dinosaur, the absence of fundamental dinosaurian characteristics demonstrates that it was not derived from a dinosaurian ancestry and should not be considered as a theropod dinosaur. Furthermore, the combination in which highly plesiomorphic non-dinosaurian traits are retained along with highly derived features, yet only the beginnings of salient birdlike characteristics, indicates that the basal origins of Aves stemmed from outside the Dinosauria and further back to basal archosaurs. Impressions of primitive elongate feathers on the forelimbs and hindlimbs suggest that Scansoriopteryx represents a basal form of ‘‘tetrapteryx’’ in which incipient aerodynamics involving parachuting or gliding was possible. Along with unique adaptations for an arboreal lifestyle, Scansoriopteryx fulfills predictions from the early twentieth century that the ancestors of birds did not evolve from dinosaurs, and instead were derived from earlier arboreal archosaurs which originated flight according to the traditional trees-down scenario. © Dt. Ornithologen-Gesellschaft e.V. 2014