Confuciusornis is a genus of primitive crow-sized birds from the Lower Cretaceous. It was found in the Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago. The bird was named after the Chinese moral philosopher Confucius (551–479 BC).
Like modern birds, Confuciusornis had a toothless beak, but close relatives of modern birds such as Hesperornis and Ichthyornis were toothed. This shows that the loss of teeth occurred more than once, in Confuciusornis and in ancestors of modern birds. This is an example of convergent evolution.
Confuciusornis is one of the most abundant vertebrates found in the Yixian Formation, and several hundred complete, articulated specimens have been found.
The proportions of the toes suggest that they were used for both walking and perching, while the large claws of the thumb and third finger were probably used for climbing. The head probably had a small crest or tuft.
The orientation of the shoulder joint was sideways, instead of angled upward as in modern birds; this means that Confuciusornis was unable to lift its wings above its back. Like Archaeopteryx, it was thus incapable of the upstroke required for flapping flight. This conclusion is not established at present. Peters sees Confuciusornis as capable of flapping flight but specialising in soaring flight. The bird's weight has also been debated.
An argument from Gregory Paul noted that Confuciusornis is commonly found as large groups in lake bottom sediments with little to no evidence of the bodies being moved after death. It would be highly unusual for gliding animals to be found in such large numbers in deep water. Rather, this evidence suggests that Confuciusornis traveled in large flocks over the lake surfaces, a habitat consistent with a flying animal.
In early 2010, a group of scientists led by Zhang Fucheng examined fossils with preserved melanosomes (organelles which contain colour pigments). By studying the fossils with an electron microscope, they found melanosomes preserved in a fossil Confuciusornis specimen. The melanosomes where of two types, which indicates that Confuciusornis had hues of grey, red/brown and black, possibly something like the modern zebra finch.
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