Austroraptor

Austroraptor (pron.:"AWE-stroh-RAP-ter") is an extinct genus of dromaeosaurid dinosaur that lived about 70 million years ago during the Cretaceous Period in what is now modern Argentina. Austroraptor was a medium sized, moderately-built, ground-dwelling, bipedal carnivore, that could grow up to 5 m (16.4 ft) long. Its length makes Austroraptor one of the largest dromaeosaurids known, with only Achillobator and Utahraptor approaching it in length. It is the largest dromaeosaur to be discovered in the Southern Hemisphere. Particularly notable about the taxon were its relatively short forearms, much shorter in proportion when compared to the majority of the members of its family.

Etymology
The genus name Austroraptor, means "Southern thief", and is derived from the Latin word auster meaning "the south wind", and the Latin word raptor meaning "thief". The specific name cabazai, was named in honor of Alberto Cabaza, who founded the Museo Municipal de Lamarque where the specimen was partially studied.[1] Austroraptor was described and named by late 2008 by Fernando Novas of the Museo Argentino de Ciencias Naturales. The type species is Austroraptor cabazai.

Anatomy
Considered large for a dromaeosaur, Austroraptor cabazai measured around 5 metres (16 ft) in length from head to tail. It is the largest dromaeosaur to be discovered in the Southern Hemisphere.[2] The type specimen, labeled MML-195, consisted of a fragmentary skeleton including parts of the dinosaur's skull, a few neck and torso vertebrae, some ribs, a humerus, and assorted bones from both legs. However little of the entire skeleton was found, what bones were available for analysis expressed some distinct characteristics that differentiate Austroraptor from other dromaeosaurs. A. cabazai's 80 centimeter-long skull was low and elongated, much more so than that of other dromaeosaurs. Several of its skull bones bore some resemblance to that of the smaller troodontid deinonychosaurs. The front limbs of this taxon were short for a dromaeosaur, with its humerus less than half the length of its femur.[2] Among the Dromaeodauridae, only this genus, Tianyuraptor and Mahakala have similarly reduced forelimbs.[3] The relative length of its arms has caused Austroraptor to be compared to another, more famous short-armed dinosaur, Tyrannosaurus.[4]

Austroraptor had conical, non-serrated teeth, which Novas et al. compared to those of spinosaurids, based on the how the enamel of the surface of its teeth is fluted.[2] Austroraptor shares a trait that is unique to it and to Adasaurus mongoliensis, the descending process of the lacrimal bones curves anteriorly to a large degree.[3] Austroraptor has a bizarre morphology in its pedal phalanges, which are strangely disproportionate. Phalanx IV-2 is over twice the width of phalanx II-2, and nearly three times the expected width based on similarly sized members of its taxonomic family.[3] This has suggested to some researchers that the holotype specimen is a chimera, which means that its bones may be from more than one individual.