Sphenocoelus

Sphenocoelus is a genus of brontothere endemic to North America during the Middle Eocene 46.2—40.4 mya), existing for approximately 6 million years.[1] Fossils have been found only in southern Wyoming and eastern Utah.[citation needed]

In life, it would have resembled a hornless rhinoceros, to which it was distantly related. However, it was smaller than modern rhinos, standing about 1.2 metres (3.9 ft) high at the shoulders, and had a much longer head. Its teeth were adapted to eating soft vegetation, such as forest leaves. Like other brontotheres, it had four toes on the front feet, and three on the hind feet, and the animal is unlikely to have been able to run fast.[2]