n.
Any hoofed, herbivorous, quadruped, placental mammal in three or four orders: Artiodactyla, the even-toed ungulates (including pigs , camels , deer , and bovines); Perissodactyla, the odd-toed ungulates (including horses , tapirs , and rhinoceroses ); Proboscidea ( elephants ); and, by some authorities, Hyracoidea (see hyrax ).
There are ten orders of extinct ungulates. The hoof is dermal tissue, comparable to the human fingernail, that extends over the end of a broadened terminal digit. See also ruminant .