An order comprising the even-toed ungulates (hoofed mammals). There are two main radiations: the predominantly omnivorous Bunodontia, including suoids (such as pigs, peccaries, and hippos); and the more herbivorous Selenodontia, including camels and ruminants (such as deer, giraffe, cattle, sheep, and antelope). Artiodactyla contains about 213 living species, making it the fifth most speciose order of mammals (exceeded primarily by rodents and bats, and slightly by carnivores and primates). First known from the early Eocene, artiodactyls have proliferated during the last 55 million years to reach great diversity (especially among the family Bovidae). Their radiation is often contrasted with that of the odd-toed ungulates, or Perissodactyla (horses, rhinos, and tapirs). Artiodactyls are also important for human economy and agriculture, comprising most of the domestic animals, providing milk, wool, and most of the meat supply. See also: Perissodactyla