Confuciusornis
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Confuciusornis Temporal range: Early Cretaceous, 125–120 Ma |
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| C. sanctus fossil preserving long wing and tail feathers. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Family: | †Confuciusornithidae |
| Genus: |
†Confuciusornis Hou et al., 1995 |
| Type species | |
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†Confuciusornis sanctus Hou et al., 1995 |
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Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago. Like modern birds, Confuciusornis had a toothless beak, but close relatives of modern birds such as Hesperornis and Ichthyornis were toothed, indicating that the loss of teeth occurred convergently in Confuciusornis and living birds. It is the oldest known bird to have a beak. It was named after the Chinese moral philosopher Confucius (551–479 BC). Confuciusornis is one of the most abundant vertebrates found in the Yixian Formation, and several hundred complete, articulated specimens have been found.
Confuciusornis was about the size of a modern pigeon, with a total length of 50 centimetres (1.6 ft) and a wingspan of up to 70 centimetres (2.3 ft). Its body weight has been estimated to have been as much as 1.5 kilograms (3.3 lb), or less than 0.2 kilograms (0.44 lb).C. feducciai was about a third longer than average specimens of C. sanctus.
Confuciusornis shows a mix of basal and derived traits. It was more "advanced" or derived than Archaeopteryx in possessing a short tail with a pygostyle (a bone formed from a series of short, fused tail vertebrae) and a bony sternum, but more basal or "primitive" than modern birds in retaining large claws on the forelimbs, having a primitive skull with a closed eye-socket, and a relatively small breastbone. At first the number of basal characteristics was exaggerated: Hou assumed in 1995 that a long tail was present and mistook grooves in the jaw bones for small degenerated teeth.
The skull of Confuciusornis was equipped with a pointed toothless beak. It was relatively heavy-built and immobile, incapable of the kinesis of modern birds that can raise the snout relative to the back of the skull. This immobility was caused by the presence of a triradiate postorbital separating the eye-socket from the lower temporal opening, as with more basal theropods, and the premaxillae of the snout reaching all the way to the frontals, forcing the nasals to the sides of the snout.
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