Rare Ichnofossil - Green River Formation Brontothere Trackway

This is an excellent ichnofossil from the Green River Formation of Sevier County, Utah that belonged to a large mammal know as a brontothere. While they looked somewhat like a rhinoceros, they were more closely related to horses. Brontotheres were browsers in warm temperate to subtropical environments and ranged from forest to open woodland. 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 fine pair of superimposed tracks provides a brief glimpse of a moment frozen for all time for some 50 million years when this massive animal walked across a muddy surface.