Another interesting mammal that spends most of its time on the prairie is the pronghorn antelope. Pronghorns are true American natives, found nowhere else in the world. they have roamed the plains and deserts of North America for at least the last million years in substantially the same form. One can truly call this animal unique: he is the lone member of his family, Antilocapra americana, which literally means the "American goat-antelope." The pronghorn has exceptionally keen vision complemented by excellent hearing and sense of smell.
Both sexes have horns, but the female's are only tiny spikes and are rarely pronged as are the twelve to eighteen-inch horns of the male. The horn is made up of two parts: a bony core covered by a black outer sheath. This sheath is made up of a stiff, hair-like substance. Pronghorns are the only animals in the world who shed their horns annually. The outer sheath of the horn falls off each fall and grows back by the following summer.