Huaxiagnathus

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iHuaxiagnathus
Fossil range: Early Cretaceous

Extinct (fossil)

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Infraorder:	Coelurosauria
Family:	Compsognathidae
Genus:	Huaxiagnathus
Species:	H. orientalis

Binomial name

Huaxiagnathus orientalis
Hwang et al., 2004

Huaxiagnathus (Hwang et al., 2004) is a compsognathid theropod from the Lower Cretaceous of the People's Republic of China. The holotype (CAGS-IG-02-301, Chinese Academy of Geological Sciences, Beijing) specimen was collected from the Yixian Formation (Jehol Group, Barremian) at Dabangou Village, Sihetun area, near Beipiao City, in western Liaoning Province. The holotype consists of an essentially complete skeleton, lacking only the distal portion of the tail, preserved on five large slabs. A second specimen (NGMC 98-5-003, National Geological Museum of China, Beijing) of Huaxiagnathus is known from the Yixian Formation of the Sihetun area, but damage and mistakes made during its preparation rendered in unsuitable as a holotype. These two specimens demonstrate that Huaxiagnathus (Mandarin Hua Xia = China + Greek gnathus = jaw) was a large compsognathid, about half a meter longer than Compsognathus and larger specimens of Sinosauropteryx. Cladistic analysis indicates that Huaxiagnathus is the basalmost known compsognathid, as indicated by its unspecialized forearm.

Hwang et al. (2004, pp. 14-15) diagnose this genus as follows: differing from all other known compsognathids in having a very long posterior process of the premaxilla that overlaps the antorbital fossa, a manus equal to the combined lengths of the humerus and radius, large manual unguals I and II which are subequal in length and 167% the length of manual ungual III, a first metacarpal which has a smaller proximal transverse width than the second metacarpal, and the presence of a reduced olecranon process on the ulna.

[edit] References

Hwang, S. H., Norrell, M. A., Qiang, J., Keqin, et. G. 2004. A large compsognathid from the Early Cretaceous Yixian Formation of China. Journal of Systematic Palaeontology 2(1):13-30.