Thursday, December 18, 2008

Austroraptor cabazai: New Gondwanan Dromaeosaurid

A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids. 2008. F. Novas, et a. Proc. Royal Soc. B. Publishedonline, December 16, 2008.

The giant raptor, Austroraptor cabazai, found in Argentina, measured 5 to 6.5 meters long, making it one of the largest raptors to roam Earth 70 million years ago.
Abstract: Fossils of a predatory dinosaur provide novel information about the evolution of unenlagiines, a poorly known group of dromaeosaurid theropods from Gondwana. The new dinosaur is the largest dromaeosaurid yet discovered in the Southern Hemisphere and depicts bizarre cranial and postcranial features.

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Its long and low snout bears numerous, small-sized conical teeth, a condition resembling spinosaurid theropods. Its short forearms depart from the characteristically long-armed condition of all dromaeosaurids and their close avian relatives.

The new discovery amplifies the range of morphological disparity among unenlagiines, demonstrating that by the end of the Cretaceous this clade included large, short-armed forms alongside crow-sized, long-armed, possibly flying representatives.

The new dinosaur is the youngest record of dromaeosaurids from Gondwana and represents a previously unrecognized lineage of large predators in Late Cretaceous dinosaur faunas mainly dominated by abelisaurid theropods.

The National Geographic story.