Hoofed mammals, also called ungulates, include around 250 species worldwide. Hoofed mammals belonging to the order Artiodactyla have paired hooves with a gap in the middle. These so-called even-toed ungulates are further subdivided into the Bovidae family (including cattle, sheep, and goats), the Cervidae family (including deer, caribou, moose, and elk), and the Antilocapridae family (including only the pronghorn in North America). In the Bovidae family, both males and females have horns that are unbranched and grow continuously, while in the Cervidae family, generally only males have branched antlers, made of bone covered with velvet that are shed and re-grown every year. Caribou are unique among the Cervidae family in that both males and females have antlers. Pronghorns are unique among the Artiodactyla in having branched horns that shed annually. The other major groups of hoofed mammals belong to the order Perissodactyla. Globally, these so-called odd-toed ungulates include horses, rhinos, and tapirs, but in North America are represented only by wild horses. Hoofed mammals are generally large-bodied plant eaters that graze or browse on vegetation, with teeth and digestive systems that are specialized for extracting energy and nutrients from plant matter.

Reference

Forsyth A: Mammals of North America: Temperate and arctic regions. Willowdale, ON: Firefly Books; 1999.