Tyrannosaurus rex was a very large theropod dinosaur that lived in what is now western North America in the Late Cretaceous Period (68-66 million years ago). It went extinct with the last of the dinosaurs at the end of the Cretaceous Period.
History
Tyrannosaurus is not only one of the most famous dinosaurs, it is also one of the first dinosaurs to be discovered in North America. The first dinosaur bones in the western part of North America were found in the 1870s. This began the ‘great dinosaur rush’, a bit like a ‘gold rush’, but these prospectors were looking for dinosaur skeletons, not gold. Expeditions from many museums converged on the area, and competed for the most dinosaurs. Many of our familiar dinosaurs like Triceratops, Stegosaurus, Allosaurus, Apatosaurs, Diplodocus, and of course Tyrannosaurus, were found by these expeditions in the final years of the 19th century and the first few years of the 20th century. Skeletons of Tyrannosaurus are very rare, but occasionally we still find a nice one, like the Tyrannosaurus nicknamed ‘Sue’ that was found in 1990 in South Dakota. It is now on exhibit in the Field Museum of Natural History in Chicago.