Anchiornis huxleyi
Aurornis is an extinct genus of anchiornithid theropod dinosaurs from the Jurassic period of China. The genus Aurornis contains a single known species, Aurornis xui (/ˈrɔːrnɪs ˈʃi/). Aurornis xui may be the most basal ("primitive") avialan dinosaur known to date, and it is one of the earliest avialans found to date. The fossil evidence for the animal pre-dates that of the Archaeopteryx lithographica, often considered the earliest bird species, by about 10 million years.

Aurornis xui was first described and named by Pascal Godefroit, Andrea Cau, Hu Dong-Yu, François Escuillié, Wu Wenhao and Gareth Dyke in 2013. The generic name is derived from the Latin word aurora, meaning "daybreak" or "dawn", and the Ancient Greek ὄρνις (órnis) meaning "bird". The specific name, A. xui, honors Xu Xing. A recent study of specimens of the avialan Anchiornis has found that the traits exhibited by Aurornis fall within the range of variation in Anchiornis, warranting their synonymization.

Aurornis was roughly the size of a modern pheasant, with a length of 50 cm (20 in). It had clawed wings and a long bony tail. Its leg bones were similar to those of Archaeopteryx, but overall its anatomy was more primitive. Aurornis lived roughly 160 million years ago, roughly 10 million years prior to Archaeopteryx, which often has been described as the first bird.

Aurornis was described from a sedimentary rock fossil in 2013. The fossil was purchased from a local dealer who said it had been unearthed in Yaoluguo in western Liaoning, China. Subsequent analysis confirmed it came from the Tiaojishan Formation, which has been dated to the late Jurassic period (Oxfordian stage), approximately 160 million years ago. The fossil features traces of downy feathers along the animal's tail, chest, and neck. It was only partially prepared at the time of purchase with the feathers not showing, and bore no signs of forgery.

On 7 June 2013, however, Science Magazine published an article which noted that Pascal Godefroit, the paleontologist who led the team that described Aurornis, reported that he is uncertain if the fossil material came from Liaoning province’'s 160-million-year-old Tiaojishan Formation, as the information provided by the fossil dealer indicated, or from the province’'s 125-million-year-old Yixian Formation, which is known to have produced several ancient bird fossils. The failure to secure rigorous provenance information casts doubt on the claim that Aurornis is 160 million years old and predates Archaeopteryx. Godefroit's team will attempt to confirm the specimen’'s provenance, and its age, by conducting mineralogical and botanical analysis on the shale slab and then publishing their findings.

A 2017 study suggested that Aurornis may be a junior synonym of Anchiornis.

This page was last edited on 30 March 2018, at 18:51.
Reference: under CC BY-SA license.

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