Hayoceros

Hayoceros is an extinct genus of the artiodactyl family Antilocapridae, endemic to North America during the Early Pleistocene epoch (1.8 mya—300,000 years ago), existing for approximately 1.5 million years.

Taxonomy
Hayoceros was named by Skinner (1942) and named as a subgenus of Tetrameryx by Frick 1937; raised to genus level. It was assigned to Antilocapridae by Skinner (1942) and Carroll (1988).

Morphology
It was about 1.8 metres (5.9 ft) in body length, and, in most respects, resembled modern pronghorns. However, in addition to the pair of forked horns located above the eyes, as in modern pronghorns, it also possessed a second, longer and unforked, pair on the back of the skull. Most likely, males used these to fight in a fashion similar to modern pronghorns, locking horns and then pushing until the opponent gave in.