or prongbuck, hoofed herbivorous mammal, Antilocapra americana , of the W United States and N Mexico. Although it is often called the American, or prong-horned, antelope, the pronghorn is the only living member of the Antilocapridae and is more closely related to the giraffe; antelopes are African and Eurasian members of the cattle family (Bovidae). The pronghorn is about the size of a goat, standing 3 ft (90 cm) high at the shoulder and weighing about 100 lb (45 kg). The coat is light brown with white underparts, two white throat stripes, and a white rump patch. The tail is short, and the ears are long and pointed. Both sexes have horns, which consist of a horny sheath and a bony core, like those of antelopes; unlike antelope horns, those of the pronghorn bear a single branch, or prong, and lose the outer sheath each year. Pronghorns live in small bands on open plains. Chiefly browsers, they feed largely on sagebrush and other shrubs, but also eat grasses. The swiftest of North…