The tyrannosaurs were a group of large carnivorous dinosaurs that roamed North America and Asia during the last part of the Cretaceous, 85 to 65 million years ago. The most famous tyrannosaur of this group is Tyrannosaurus, a dinosaur well known to every school child. Traditionally, the tyrannosaurs have been included as part of a larger group of carnivorous dinosaurs know as the carnosaurs. In this scheme, carnosaurs represent the largest carnivorous animals to ever walk the land. However, recent work has suggested that tyrannosaurs may in fact be a highly derived group of coelurosaurs, a group of meat-eating dinosaurs that is more traditionally comprised of small animals.
Henry Fairfield Osborn, of the American Museum in New York City, first described Tyrannosaurus rex in 1905. This first specimen of Tyrannosaurus can now be found on display at the Carnegie Museum of Natural History in Pittsburgh. Clearly this animal was imposing in size and stature. It stood approximately four to six meters high, and was close to 50 feet in length. In its large mouth were enormous six inch long, sharp, serrated teeth. Yet despite all of this, it remains to be demonstrated that tyrannosaurs, and particularly Tyrannosaurus, were the predominant carnivorous animals inhabiting the terrestrial environment of the time. There have been less than two dozen good specimens of these animals found, and these finds are from highly restricted areas on two continents.
