Aurornis
Aurornis | |
---|---|
Life restoration | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Family: | †Anchiornithidae |
Genus: | †Aurornis Godefroit et al., 2013 |
Type species | |
†Aurornis xui Godefroit et al., 2013
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Aurornis is an
Aurornis xui was first described and named by Pascal Godefroit, Andrea Cau, Hu Dong-Yu, François Escuillié, Wu Wenhao and Gareth Dyke in
Description
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.[2] Aurornis lived roughly 160 million years ago, roughly 10 million years before Archaeopteryx, which often has been described as the first bird.[2]
Discovery
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.[1][4][5] 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.[2]
On 7 June 2013, Science Magazine published an article that 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.[6] 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
Classification
A
The classification of A. xui as a bird is somewhat contentious, however, due to the various differing definitions of the word "bird". Recent discoveries "[emphasize] how grey the dividing line is between birds and [non-avian] dinosaurs", says Paul Barrett of the Natural History Museum in London. "There's such a gradation in features between them that it's very difficult to tell them apart ... [Aurornis xui] is certainly an older member of the bird lineage than Archaeopteryx, and it's fair to call it a very primitive bird. But what you call a bird comes down to what you call a bird, and a lot of definitions depend on Archaeopteryx."[2] Bird evolution specialist Lawrence Witmer called the new analysis compelling, but said it remains difficult to distinguish birds from birdlike dinosaurs: "All of these little feathered species running and flapping around ... were all very similar."[10]
American paleontologist Luis Chiappe said that A. xui's forelimb is too short for this species to be a true bird. It "is very birdlike, but it is not yet a bird," he concluded.[11]
In his 2002 book Dinosaurs of the Air,
References
- ^ S2CID 4364892.
- ^ a b c d e f Ian Sample (May 29, 2013). "Early bird called Dawn beat Archaeopteryx to worm by 10m years". The Guardian. Retrieved May 29, 2013.
- ^ S2CID 90650697.
- S2CID 205218015.
- .
- PMID 23744916.
- ^ Jonathan Amos (May 29, 2013). "Archaeopteryx restored in fossil reshuffle". BBC. Retrieved May 29, 2013.
- PMID 25264248.
- PMID 29197327.
- ^ "Dinosaur or bird? New study restores famed fossil to 'bird' branch". Fox News. Associated Press. May 29, 2013. Retrieved May 29, 2013.
- ^ Rachel Ehrenberg (May 29, 2013). "Fossil muddies the origin of birds". Science News. Archived from the original on June 7, 2013. Retrieved May 29, 2013.
- ^ Paul, G.S., 2002, Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds, Johns Hopkins University Press, 473 pp
- ^ Cau, A. "Aurornis xui: nuova luce sull'origine degli uccelli", Theropoda: The Most Inclusive Blog containing Allosaurus fragilis but not Saltasaurus loricatus accessed 3 November 2013
- ^ Yong, Ed (2013-05-29). "The Changing Science of Just-About-Birds and Not-Quite-Birds". Archived from the original on June 8, 2013. Retrieved 2015-07-24.