Dinosaurs in Their Time

DinoGuide: Tyrannosaurus rex

T. rex skullArguably the most famous dinosaur, Tyrannosaurus rex was one of the largest predators ever to have walked the earth.

Carnegie Museum's specimen is especially important because it is the holotype of the species Tyrannosaurus rex. A holotype is a specimen that serves as the basis for the original description of a species. To read about the history of how T. rex came to the museum, visit the PaleoLab journals!

The skull of Tyrannosaurus rex was up to 5 feet (1.5 meters) long and equipped with 6-inch (15 cm) teeth. It could deliver a powerful, crushing bite. Although more massive than the skull of Allosaurus, the weight of the skull of Tyrannosaurus rex was reduced by large openings in the sides of the skull. In addition to the holes for the nostrils and eyes, there are four additional openings, reducing most of the skull to a network of strut-like braces of bones.

T. rex had massive hind legs and large, three-toed feet. The arms were small but strong, and each hand had only two functional digits. The heavy tail counterbalanced the great body weight over the hips.

T. rexCARNEGIE SPECIMEN NUMBER:
CM 9380

SCIENTIFIC NAME MEANING:
"Tyrant king reptile"

CLASSIFICATION:
Dinosauria : Saurischia : Theropoda : Tyrannosauridae

LENGTH:
Up to 46 feet (14 meters)

GEOLOGICAL FORMATION & LOCALITY:
Hell Creek Formation; Hell Creek, Garfield County, Montana

COLLECTOR:
Barnum Brown, American Museum of Natural History, 1902–1903

TIME PERIOD:
Late Cretaceous, 65–70 million years ago

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