Unenlagia

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This article is about the dinosaur. For the Zoid by the same name, see Unenlagia (Zoids)

Unenlagia
Fossil range: Late Cretaceous

Extinct (fossil)

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Infraorder:	Coelurosauria
Family:	Dromaeosauridae
Subfamily:	Unenlagiinae
Genus:	Unenlagia Novas and Puerta, 1997

Species

U. comahuensis (type)
U. paynemili Calvo, Porfiri & Kellner, 2004

Unenlagia (meaning "half-bird"^{[verification needed]}) was a genus of theropod dinosaur of the family Dromaeosauridae. Unenlagia, which lived in South America during the Late Cretaceous, was a member of the strange and extremely bird-like Gondwanan sub-family of dromaeosaurs called unenlagiines, and was closely related to dinosaurs such as Buitreraptor and Neuquenraptor (which might be the same species as Unenlagia). Makovicky et al. (2005) suggested that the 'flying raptor' Rahonavis is also a member of this group, which could mean that Unenlagia is secondarily flightless, having evolved from flying, Rahonavis-like ancestors. Norell et al. (2006) also found Rahonavis to be the sister taxon of Unenlagia.

Unenlagia was very birdlike itself. Novas and Puerta (1997) found its pelvic region to be very similar to that of the early bird Archaeopteryx. The shoulder girdle of Unenlagia also shows adaptations for flapping. At 2 meters (6 feet) long, Unenlagia was probably too big to fly; thus either it evolved from flying ancestors, or Rahonavis (if an unenlagiine) evolved flight from adequately adapted (but too large; see also exaptation) dromaeosaurs independently of the Archaeopteryx lineage, at a time when other bird lineages were already undergoing vigorous adaptive radiation.

[edit] References

Calvo, J.O., Porfiri, J.D. and Kellner, A.W. (2004). On a new maniraptoran dinosaur (Theropoda) from the Upper Cretaceous of Neuquén, Patagonia, Argentina. Arq. Mus. Nacional. Rio de Janeiro 62: 549?566.
Makovicky, Apesteguía and Agnolín (2005). The earliest dromaeosaurid theropod from South America. Nature. 437, 1007-1011.
Norell, M.A., Clark, J.M., Turner, A.H., Makovicky, P.J., Barsbold, R., and Rowe, T. (2006). "A new dromaeosaurid theropod from Ukhaa Tolgod (Omnogov, Mongolia)." American Museum Novitates, 3545: 1-51.
Novas, F.E. and Puerta, P.F. (1997). New evidence concerning avian origins from the Late Cretaceous of Patagonia. Nature 387: 390-2.