Green River Formation Titanothere Tooth Fossil

This is a nearly complete tooth from the Green River Formation of Bridger County, Wyoming that belonged to a large mammal know as a titanothere. While they looked somewhat like a rhinoceros, they were more closely related to horses. They evolved rapidly from their Eocene members to ones rivaling the size of the elephant by the Oligocene, only to become extinct by the end of the Oligocene with the proliferation of grasslands.. Complete mammalian fossils are quite rare, and to date consist entirely of bats, with others usually only teeth or bone fragments. This one was found fragmented, but was easily reassembled based upon the clean contacts between pieces.