Even-toed hoofed mammals; the mammalian order that includes hippopotamuses, pigs, peccaries, camels, chevrotains, cattle, antelopes, deer, giraffes. Among living mammals, probably the closest relatives of whales. ("Encyclopedia of Marine Mammals," William F. Perrin, Bernd Wursig and J.G.M. Thewissen, Academic Press, 2002, p. 1348.)

terrestrial herbivorous mammals characterized by having an even number of toes and by having the main limb axes pass between the third and fourth toes examples include: hippos (4 toes), deer, sheep, antelope, goats (2 toes)