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''Sapeornis'' is a genus of primitive avialans which lived during the Early Cretaceous (late Aptian to early Albian, roughly 125-120 mya). The genus contains only the species ''Sapeornis chaoyangensis'' which is known from fossils found in Jiufotang Formation and Yixian Formation rocks in the People's Republic of China. Several nearly complete skeletons have been found.〔Zhou, Zhonghe & Zhang, Fucheng (2003): Anatomy of the primitive bird ''Sapeornis chaoyangensis'' from the Early Cretaceous of Liaoning, China. ''Canadian Journal of Earth Sciences'' 40(5): 731–747. (HTML abstract)〕 ''Sapeornis'' is named for SAPE, the Society of Avian Paleontology and Evolution, added to the Ancient Greek ''όρνις'' (ornis), meaning "bird". ''chaoyangensis'' is Latin for "from Chaoyang". ==Description== This animal was about 30–33 cm long in life, excluding the tail feathers (which are unknown). From its general morphology and some peculiar similarities with oviraptorosaurs such as ''Caudipteryx'', it is usually considered to be fairly close to ''Omnivoropteryx''.〔Czerkas, S. A. & Ji, Q. (2002): A preliminary report on an omnivorous volant bird from northeast China. ''In'': Czerkas, S. J. (editor): ''Feathered Dinosaurs and the origin of flight. The Dinosaur Museum Journal'' 1: 127-135. (HTML abstract )〕 The hand of ''Sapeornis'' was far more advanced than that of ''Archaeopteryx''. It had three fingers, the outer ones with two and the middle one with three phalanges, and a well-fused carpometacarpus. Its arms were about half again as long as the legs, suggesting a large wing area. On the other hand, its shoulder girdle was apparently ill-adapted to flapping flight and its furcula was unusual, with a hypocleidum similar to more advanced avialans but a general anatomy even more primitive than in ''Archaeopteryx''. The humerus was large and bore holes, apparently to save weight, as in the Confuciusornithidae. The skull has a handful of teeth in the upper jawtip only. ''Sapeornis'' had gastralia but no (or unossified) uncinate processes. A sternum was either not present or small and easily lost. The pygostyle was rod-like as in ''Confuciusornis'' and ''Nomingia'', but like in the former there was no long bony tail anymore. While the tarsometatarsi were more fused than in ''Archaeopteryx'', the fibula was long and reached the distal point of the tarsal joint, not reduced as in more modern birds (and some non-avian theropods like ''Avimimus''). The first toe pointed backwards. In specimen IVPP V12375, the stomach contained numerous small gastroliths. Analysis of its skeletal bones suggest that it had an ontogeny and slow growth like ''Archaeopteryx'' and small carnivorous dinosaurs, rather than the explosively fast growth seen in modern birds. In absolute number of features shared with modern birds, ''S. chaoyangensis'' is about as advanced as ''Confuciusornis''. However, the apomorphies were largely different from ''Confuciusornis'', and a character analysis demonstrates that these two were not closely related. The tail plumage of ''Sapeornis'' consisted of rectrices that formed a graded, fan-like structure. The reduced fingers suggest that it might have had an alula. Not being well-adapted to flapping flight, ''Sapeornis'' probably was a glider and/or soarer that preferred more open country compared to the Enantiornithes and predominantly woodland birds, although it was able to perch on branches. The small gastroliths, overall large size, and the inferred habitat indicate that ''Sapeornis'' was most likely a herbivore, possibly eating plant seeds and fruits.〔 Comparisons between the scleral rings of ''Sapeornis'' and modern birds and reptiles indicate that it may have been diurnal, similar to most modern birds. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sapeornis」の詳細全文を読む スポンサード リンク
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