Tyrannosaurus lived in the late Cretaceous of North America. Its fossils have been found in an area now known as the Hell Creek Formation. At the time, this area was a flat, forested floodplain with a relatively subtropical climate. This climate supported a variety of plants, including angiosperm trees, conifers, ferns, and ginkgoes. The presence of crocodile fossils suggests a warm climate with no cold season, and ample rain.