Hayoceros

Hayoceros was named by Skinner (1942) and named as a subgenus of Tetrameryx by Frick 1937; it was later raised to genus level. It was assigned to the Antilocapridae by Skinner (1942) and Carroll (1988).^[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.^[4]