The even-toed ungulates form the mammal order Artiodactyla, the group that contains the pigs, peccaries, hippopotamuses, camels, chevrotains (mouse deer), deer, giraffes, pronghorn, antelopes, sheep, goats, and cattle. They are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in odd-toed ungulates (perissodactyls). Another key distinguishing feature is the shape of the astr...
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The even-toed ungulates form the mammal order Artiodactyla, the group that contains the pigs, peccaries, hippopotamuses, camels, chevrotains (mouse deer), deer, giraffes, pronghorn, antelopes, sheep, goats, and cattle. They are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in odd-toed ungulates (perissodactyls). Another key distinguishing feature is the shape of the astragalus, a bone in the ankle joint, which has a double-pulley structure. This gives the foot greater flexibility.
There are about 220 artiodactyl species, including many that are of great nutritional, economic and cultural importance to humans.
As with many mammal groups, even-toed ungulates first appeared during the Early Eocene (about 54 million years ago). In form they were rather like today's chevrotains: small, short-legged creatures that ate leaves and the soft parts of plants. By the Late Eocene (46 million years ago), the three modern...
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