STL Science Center

STL Science Center

27 September 2014

Being Different

Usually when we think of tyrannosaurs we think of Tyrannosaurus rex and Tarbosaurus bataar and other large headed theropods that used their large teeth and bulk to hunt down, overpower, and subdue their prey. The Proceratosauridae were rather different members of the tyrannosaur family. A global distribution has been identified in the family as it contains English, Chinese, Russian, and American found fossil species. The namesake of the family is Proceratosaurus, a small Jurassic, English, tyrannosaur that was most likely capable of hunting in the dense forests that its larger later cousins may not have been able to penetrate. Along with Proceratosaurus and other small members of the Proceratosauridae, Stokesosaurus was probably a small but quick tyrannosaur that used its speed and hands in attacking prey. The differences between the more basal members of this family and the more advanced and larger tyrannosaurs are centered mainly around the heads and hands. All members of the Proceratosauridae appear to have much more streamlined heads that are more gracile and less muscular. The heads of these animals still possess tyrannosaurid characteristics but are much more primitive in shape and build. The hands are also more primitive. Advanced tyrannosaurs have shortened forelimbs and reduced digits on the hand. Proceratosauridae have slightly longer forearms, respective to body size, and a greater number, though still reduced, of digits in the hand. Exceptions and preservational bias can affect these traits in the family, but overall these generalizations can be applied to the family.

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