Sinornis
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Sinornis Temporal range: Early Cretaceous, 135 Ma |
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| Reconstruction of Sinornis | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | †Enantiornithes |
| Genus: |
†Sinornis Sereno & Rao, 1992 |
| Species: | †S. santensis |
| Binomial name | |
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Sinornis santensis Sereno & Rao, 1992 |
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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 as 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).
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. 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. Analogous to Archaeopteryx and theropod dinosaurs, its pubis appears to be directed more ventrally and terminates distally in a hook shaped.
As in Archaeopteryx, the skull of Sinornis has a proportionately short, toothed snout, with separate carpus and manus in the forelimb. Its skull and postcranial had short snout, teeth, and pelvic with footed pubis and gastralia. The manus is composed of freely articulating metacarpals, with well-formed phalanges and unguals on the first and second digits. Had a broad nasal that expands caudally to external nares, with a triangular caudal margin. The dorsal and central margins of caudal half of the maxilla are parallel with Jugal ramus does not taper caudally.
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