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Sinornis
''Sinornis'' is a genus of enantiornithine birds. The fossils recovered from the Lower Cretaceous lake deposits from the Jiufotang Formation at Liaoning, People's Republic of China. This 135 million-year-old sparrow-sized skeleton represent a new avian which shares primitive features with ''Archaeopteryx'' and well as modern birds. Its primitive features include, but are not limited to a flexible manus with unguals, a footed pubis, and stomach ribs. As well as shedding a new light on the early evolution of avian flight and perching that lead to modern birds. ''Sinornis'' is known only from the type species, ''Sinornis santensis'', from the words ''sino'', 'China'; ''ornis'', 'bird'; and the word ''santensis'', meaning "from three temples" (for the traditional Chinese name for Chaoyoung county in Liaoning Province where the bird skeletons were found).〔
==Description==
The holotype skeleton of ''Sinornis'' is preserved on part and counterpart slabs of fine-grained freshwater lake sediment and is associated with abundant fish, insect, and plant remains.〔Sereno, P. C., & Rao, C. (1992). "Early evolution of avian flight and perching: New evidence from the lower Cretaceous of China". ''Science'', 255(5046), 845.〕 The skeleton remains found in Jiufotang Formation at Liaoning, People's Republic of China. The skeleton exhibits remarkable primitive features with ''Archaeopteryx'', a genus of early bird that is transitional between feathered dinosaurs and modern birds. Until the discovery of ''Sinornis'' scientists did not know much about the evolution of flight that lead to modern birds because ''Archaeopteryx'', which lived in the Late Jurassic period around 150 million years ago, lacks many of the modern flight and perching of modern birds.〔 Some of the primitive features found in ''Sinornis'' include moderately recurved manual unguals, as opposed to the high-recurved one in ''Archaeopteryx''. ''Sinornis'' shares similar pelvis with the latter genus, but its pelvic girdle is free unlike the ossified ones found in modern birds. The iliac blades are erect and the ischium that is blade-shaped rather than strap-shaped.〔Dyke, G.J. & Nudds, R.L. 2009: "The fossil record and limb disparity of enantiornithines, the dominant flying birds of the Cretaceous". ''Lethaia'', Vol. 42, pp. 248–254.〕 Analogous to ''Archaeopteryx'' and theropod dinosaurs, its pubis appears to be directed more ventrally and terminates distally in a hook shaped.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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