pronghorn 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, it does not belong to the true antelope family of Africa and Asia, but to a related family, the Antilocapridae, of which it is the only living member. 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 American mammals, they attain speeds of 60 mi (96 km) per hr, but are poor jumpers. Their principal enemies, besides humans, are wolves and coyotes. Before the settlement of North America by Europeans pronghorns were comparable in numbers to buffalo; by the beginning of the 20th cent., however, they had been nearly exterminated by hunting. They are now protected on reservations, where they have made a good recovery. Pronghorns are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Artiodactyla, family Antilocapridae.

Ruminant (Antilocapra americana) of North American plains and semideserts, the only living member of the family Antilocapridae. The pronghorn stands 30–40 in. (80–100 cm) tall. It is reddish brown with a short, dark-brown mane, white underparts, two white bands on the throat, and a circular white patch on the rump. Both sexes bear erect, two-pronged horns; the longer prong curves backward, the shorter prong forward. Pronghorns live alone or in small bands in summer, and in large herds in winter. The fastest mammal of North America, the pronghorn can run 45 mph (70 kph) and can bound up to 20 ft (6 m). Though tens of millions once roamed the West, they were nearly exterminated by hunters in the early 20th century; conservation efforts have since allowed their populations to increase.

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