Tyrannosaurus rex was one of the largest theropod dinosaurs that ever existed. Its scientific name, Tyrannosaurus ('tyrant lizard') rex ('king') says it all. It lived in what is now western North America in the latest Cretaceous (68-66 million years ago). T. rex went extinct at the very end of the Cretaceous, and so is one of the last dinosaurs to have lived on earth.
Tyrannosaurus rex is one of the very first dinosaurs to bediscovered and described. Isolated teeth and other isolated boneswere found in the American west as early as 1872, but no one wassure what sort of animal they belonged to. In 1900, Barnum Brown, afamous collector working at the American Museum of Natural History,discovered the first T. rex skeleton in Wyoming. Over the next fiveyears, he found four more skeletons, although none of them wascomplete. Henry Osborn, also of the American Museum of NaturalHistory, described and named Tyrannosaurus rex in 1905 based on this material. Thelargest of Brown's skeletons can be seen on display at the AmericanMuseum, and another is on display at the Cleveland Museum onNatural History. After these initial finds, T. rex skeletons proved to be rare, but occasionally, newskeletons have come to light. One of the most famous is a T. rex called 'Sue' (guess what gender paleontologists thinkit is) that was collected in 1990 in South Dakota, and is now onexhibit at the Field Museum of Natural History in Chicago. It isthe most complete skeleton of T. rex, with nearly every single bone preserved inplace.