See text Sphenocoelus is an extinct 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.