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'''Sapeornis'''^[1]
is a genus of primitive bird, or protobird, which lived during the Early Cretaceous (Barremian to early Aptian, roughly 130-120 mya). The genus contains only the species '''Sapeornis chaoyangensis''' which is known from fossils found in Jiufotang Formation rocks near Chaoyang, PRC. Several nearly complete skeletons have been found (Zhou & Zhang 2003).
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 & Ji 2002).
The hand of ''Sapeornis'' was far more advanced than that of ''Archaeopteryx''. It had 3 fingers, the outer ones with 2 and the middle one with 3 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 the hypocleidum of more advanced birds but a general conformation even more primitive than in ''Archaeopteryx'' (Senter 2006). 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. It was altogether similar to ''Archaeopteryx'', but even more so to small oviraptorosaurs and ''Omnivoropteryx''.^[2] ''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 as there, 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.
In conclusion, regarding the absolute numbers of modern bird features, ''S. chaoyangensis'' about as more advanced than ''Archaeopteryx'' as was ''Confuciusornis''. However, the apomorphies were largely different from ''Confuciusornis'', and a character analysis demonstrates that these two were not closely related (Zhou & Zhang 2006). As its plumage is not known yet, the airfoil shape of ''Sapeornis'' is unknown. As indicated by the slender pygostyle, its tail plumage was (unlike in the reconstruction above) probably short as in the Enantiornithes or even vestigial as in ''Confuciusornis''. 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 other 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.(Zhou & Zhang 2003)

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References

Footnotes

External links

References

★ '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

★ 'Senter', Phil (2006): Scapular orientation in theropods and basal birds, and the origin of flapping flight. ''Acta Palaeontologica Polonica'' '51'(2): 305–313. PDF fulltext

★ '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)

★ 'Zhou', Zhonghe & 'Zhang', Fucheng (2006): A beaked basal ornithurine bird (Aves, Ornithurae) from the Lower Cretaceous of China. ''Zool. Scripta'' '35': 363–373. (HTML abstract)

Footnotes

1.
Etymology: ''Sapeornis'' from SAPE, the 'S'ociety of 'A'vian 'P'aleontology and 'E'volution [1] + Ancient Greek ''ornis'', "bird". ''chaoyangensis'', Latin for "from Chaoyang".
2. http://dml.cmnh.org/2003Jun/msg00374.html

External links

★ The Dinosauricon: ''Sapeornis chaoyangensis'' head restoration by Gareth Monger, 2007. Retrieved 2007-MAY-01.

★ The Dinosauricon: ''Sapeornis chaoyangensis'' restoration by Martin F. Chavez H., 2007. Retrieved 2007-MAY-01.

★ The Dinosauricon: ''Sapeornis chaoyangensis'' skeleton drawing by Jaime Headden, 2007. Retrieved 2007-MAY-01.

★ The Dinosauricon: ''Sapeornis chaoyangensis'' skeleton drawing and restoration by Scott Hartman, 2007. Retrieved 2007-MAY-01.