Description

Hyracodon was a sporty, slender-limbed, pony-sized rhino of the Late Eocene to Early Miocene of western North America.  It lived at a time when the tropical forests of the Early-Middle Eocene had been largely replaced by open woodlands.  Hyracodon disappeared just before grasslands began to dominate large areas of all but one of the continents.

Known today as large and formidable beasts of Asia and Africa, rhinos took on many shapes and sizes from the agile Hyracodon to the largest land mammal of all time, Paraceratherium, which would have towered over the tallest mammoth.

Most finds are isolated teeth or bones but here is a nice jaw section with six teeth.  You would not expect to find something like this in a day of hunting.

Early Oligocene
Brule Formation
White River Badlands, South Dakota, USA
120mm jaw section with 6 teeth
Mammal, Hyracodontidae