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

[2][3] It was about 1.8 m (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 gives in.

This prehistoric even-toed ungulate-related article is a stub.