Atrociraptor: Beast of the Week

 This week we'll be covering a unique predator that will be makes its big screen debut in the movie, Jurassic World: Dominion.  Let's check out Atrociraptor marshalli!

Atrociraptor was a meat-eating dinosaur that lived in what is now Alberta, Canada, during the late Cretaceous period, about 68.5 million years ago.  It is estimated to have measured a little over 6 feet long (2 meters) from snout to tail when alive, but this is based on only some skull pieces and scaling them to more completely known relatives.  The genus name translates to "Atrocious Thief". 

Atrociraptor life reconstruction in watercolors. By Christopher DiPiazza

Atrociraptor was a member of the dromaeosaurid family of dinosaurs.  Dromaeosaurids were famous for being relatively small, relatively fast-moving predators with a long retractable claw on the second toe of each foot.  Deinonychus and Velociraptor are the two most famous members of this group.  There are many dromaeosaurids that were discovered possessing fossilized feathers or direct evidence of feathers, so it is almost certain that being feathered was a universal trait to this group, meaning Atrociraptor likely would have been feathered in life as well.  

Unfortunately Atrociraptor is only known from some skull material, specifically the tips of the upper and lower jaws, and teeth.  Based on this, however, scientists were still able to tell it was a dromaeosaurid by the size and number of serrations on the slightly curved, blade-like teeth, which are diagnostic to the family.  Atrociraptor's teeth weren't as curved as those of some other meat-eating dinosaurs, but they were arranged in the jaw so that the tips were dramatically angled to the back of the mouth, which would have helped the dinosaur get chunks of flesh down faster as it tore them off.  This also would prevent living prey from escaping if it was bitten.  Based on the actual jaws, Atrociraptor would have had an unusually short, but deep snout, which is in contrast to its relative, Velociraptor, known for having a particularly long, narrow one.  

Fossil specimen of Atrociraptor's jaws. (photo by Emily Willoughby)

Despite what is often portrayed in movies, we have no idea if Atrociraptor hunted in groups or alone in life.  Like many meat-eaters today, there is a chance it may have done a bit of both depending on what kind of prey was available.  We may never know for sure! 

Atrociraptor would have shared its habitat with other dinosaurs, like, Anodontosaurus, Hypacrosaurus, and Pachyrhinosaurus, Sphaerotholus?  It also would have been weary of the large tyrannosaurid, Albertosaurus.  

References

Currie, P. J. and D. J. Varricchio (2004). "A new dromaeosaurid from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada". Pp. 112–132 in P. J. Currie, E. B. Koppelhus, M. A. Shugar and J. L. Wright. (eds.), Feathered Dragons. Indianapolis: Indiana University Press.

Larson, D. W., Brinkman, D. B., & Bell, P. R. (2010). Faunal assemblages from the upper Horseshoe Canyon Formation, an early Maastrichtian cool-climate assemblage from Alberta, with special reference to the Albertosaurus sarcophagus bonebed This article is one of a series of papers published in this Special Issue on the theme Albertosaurus. Canadian Journal of Earth Sciences, 47(9), 1159-1181.

Lü, Junchang; Brusatte, Stephen L. (2015). "A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution". Scientific Reports. 5: Article number 11775.

Turner, A.H.; Makovicky, P.J.; Norell, M.A. (2007). "Feather quill knobs in the dinosaur Velociraptor". Science. 317 (5845): 1721.

Xu, Xing; Zhou, Zhonghe; Wang, Xiaolin; Kuang, Xuewen; Zhang, Fucheng; Du, Xiangke (2003). "Four-winged dinosaurs from China". Nature. 421 (6921): 335–340.