4. Hoofed mammals are divided into two subgroups. The even-toed hoofed mammals have four toes, but only walk on two of the four. This group includes deer, antelope, cows, camels, hippopotami, goats, pigs, and sheep. Odd-toed mammals walk on one or three toes. Horses, donkeys, zebras, rhinoceroses, and tapirs are in this group.