Pronghorn are endemic to North America, and are the only living members of the family Antilocapridae. In the Pleistocene, about a dozen species roamed the continent. Two things distinguish their horns from those of all other mammals: they fork, and the black, outer, forked sheath is shed annually from the unforked, bony core. The horns of females are shorter and do not develop a pronounced prong-like shape. Pronghorns stay in the open, relying on their excellent eyesight and speed for protection - they have been clocked at 72 km per hour. They communicate with each other visually, by raising the mane on the back of the neck into a stiff brush and erecting the white hairs on the rump. When a Pronghorn activates this visual beacon, it is coupled with an olfactory signal: the rump glands emit a strong smell.

Adaptation: Pronghorn have large eyes projecting away from the skull. A prominent ring-like eye socket supports the eyes, giving them a very wide field of view.

Links:
Mammal Species of the World