Yandangornis
Yandangornis | |
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Holotype specimen
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | Avialae |
Clade: | †Yandangithiformes Cai & Zhao, 1999 |
Family: | †Yandangithidae Cai & Zhao, 1999 |
Genus: | †Yandangornis Cai & Zhao, 1999 |
Species: | †Y. longicaudus
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Binomial name | |
†Yandangornis longicaudus Cai & Zhao, 1999
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Yandangornis is a
Discovery and naming
The holotype specimen is a mostly complete skeleton in the collection of the Zhejiang Museum of Natural History, with accession number M1326. The fossil was discovered in 1986, near Linhai City in Zhejiang Province, China. It includes most of one complete skeleton. The genus was named after the Yandang mountains.
Description
The specimen is small, roughly the size of
The skull is flattened, about 50 millimetres (2.0 in) long. It is lightly built and toothless, with a short mouth and robust
Yandangornis had some features that suggest a terrestrial mode of life, such as blunt toe claws, a non-reversed hallux of the first toe, and strong legs. This lifestyle may have evolved in response to the long, heavy tail of the genus, which would have inhibited flying ability.[1]
Classification
Cai and Zhao placed Yandangornis in a monotypic family (Yandangithidae) and order (Yandangithiformes) in the subclass Sauriurae of the class Aves. In fact, they considered that it was a direct descendant of Archaeopteryx, albeit as part of a lineage of long-tailed terrestrial birds distinct from modern birds.[1] However, Sauriurae (long-tailed birds) has generally been discredited as an invalid paraphyletic group.[2] Aves, on the other hand, is currently restricted to the last common ancestor of all living birds and its descendants. As Yandangornis was far more primitive than members of Aves, it is not considered a member of that class using recent definitions. The usage of Aves within the description of Yandangornis more closely resembles the current clade Avialae, which is defined as all animals more closely related to modern birds (Aves) than to Troodontids and Dromaeosaurids.[3] Other long-tailed avialans include Jeholornis and Archaeopteryx.
Zhou and Zhang, 2007, briefly noted that Yandangornis's affinities were not sufficiently diagnosed, and that Yandangornis may potentially be a non-avialan genus of theropod.[4] Yandangornis is poorly documented in literature, and discussion of the genus has generally been omitted from recent reevaluations of avialan systematics.
References
- ^ ISSN 1006-9313
- ^ Gauthier, Jacques, de Queiroz, Kevin. (2001) "Feathered dinosaurs, flying dinosaurs, crown dinosaurs, and the name 'Aves'". in "New Perspective on the Origin and Evolution of Birds: Proceedings of the International Symposium in Honor of John H. Ostrom" Yale Peabody Museum. Yale University. New Haven, Conn. USA
- S2CID 4364892.
- ^ Zhou, Zhonghe, Zhang, Fucheng. (2007) "Mesozoic birds of China––a synoptic review." "Frontiers of Biology in China" 2(1):1-14