Tyrannosaurus dinosaur, illustration. The trigeminal nerve (white) is shown in this view. The trigeminal nerve and its branches produce sensation in the face, as well as functions such as biting and chewing. The type species of this dinosaur, Tyrannosaurus rex, lived in North America and Asia from about 70 million years ago until the extinction of the dinosaurs some 5 million years later. The head was heavily built, to withstand impacts with prey animals, and has the sharp teeth of a predator. T. rex is thought to have been a scavenger as well as a hunter. Among the largest carnivorous dinosaurs, it was up to 6 metres tall and weighed as much as 7 tonnes.