The badlands of the western US are particularly rich in mammal fossils
from the late Eocene to Miocene. The Brule Formation is exposed
over a huge area including Nebraska, North and South Dakota, Wyoming,
and Colorado, and yields abundant fossils as layers are eroded.
This diverse group of stocky prehistoric mammals grazed amid the
grasslands, prairies or savannas of North and Central America throughout
much of the Cenozoic era.
is an extinct mammal distantly related to pigs, hogs, camels, hippopotamuses,
and the pig-like peccaries. Over 50 species of Oreodonta have been
described. They first appeared some 50 million years ago during
the warm Eocene and were widely prevalent during the Oligocene in
the grasslands, prairies or savannas of what is now the North American
badlands. The Oreodonts mysteriously disappeared
some four million years ago during the Pliocene.
Today, fossil jaws and teeth of the Oreodonta are commonly found
in the White River badlands in South Dakota, Nebraska, and Wyoming.
Oreodonts have a unique place in the evolution of ruminant teeth
and with peccary-like attributes. Oreodonts are Artiodactyls, even
toed ungulates, sometimes called a cross between a pig and a sheep.
Note that they have both large canine front teeth, but also molars
for chewing plants. They were herding animals and grazers, eating
mostly grasses. They averaged three to four feet long.
is an excellently preserved skull. It is unusually large with well
preserved teeth and bone, with little or no restoration.