Eucoelophysis

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Eucoelophysis
Fossil range: Late Triassic

Extinct (fossil)

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Infraclass:	Archosauromorpha
(unranked)	Ornithodira
(unranked)	Dinosauriformes
Genus:	Eucoelophysis

Binomial name

Eucoelophysis baldwini
Sullivan & Lucas, 1999

Eucoelophysis (meaning "true hollow tail") is a genus of dinosauriform from the Late Triassic period of North America. It was assumed to be a coelophysid upon description, but a 2005 study by Nesbitt et al. found that it was actually a close relative of Silesaurus, which was independently supported by Ezcurra (2006), who found it to be the sister group to Dinosauria, and Silesaurus as the next most basal taxon.^[1]^[2]

However, the relationships of Silesaurus are uncertain. Dzik found it to be a dinosauriform (the group of advanced archosaurs from which true dinosaurs evolved), but did not rule out the possibility that it represents a primitive ornithischian.^[3]

[edit] References

^ Nesbitt, S.J., Irmis, R.B., and Parker, W.G. (2005). "A critical review of the Triassic North American dinosaur record." In Kellner, A.W.A., Henriques, D.D.R., & Rodrigues, T. (eds.), II Congresso Latino-Americano de Paleontologia de Vertebrados, Boletim de Resumos. Rio de Janeiro: Museum Nacional/UFRJ, 139.
^ Ezcurra, M.D. (2006). "A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini Sullivan & Lucas, 1999 from the Upper Triassic of New Mexico, USA." Geodiversitas, 28(4):649-684.
^ Dzik, J. (2003). "A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland." Journal of Vertebrate Paleontology, 23(3): 556-574.