In the hot and humid forests of Eocene North America around 56 million years ago, Uintatherium anceps is having breakfast. Despite its resemblance to modern rhinoceroses, Uintatherium was not related to them but rather belonged to an extinct order of mammals known as the Dinocerata, which lived between the Paleocene and Eocene epochs of the early Cenozoic Era. One 2015 study has suggested a closer relationship between Dinocerata on the one hand and an order of South American hoofed mammals, also extinct, called the Xenungulata.