The last section of the Artiodactyla is that of the Suina, represented at the present day by the pigs (Suidae), and the hippopotamuses (Hippopotamidae), and in past times by the Anthracotheriidae, in which may probably be included the Elotheriidae.
As contrasted with the Perissodactyla living, and in a great degree extinct, Artiodactyla are characterized by the following structural features.
The Artiodactyla are the only group of ungulates known to have been represented in Madagascar; but since both these Malagasy forms - namely two hippopotamuses (now extinct) and a river-hog - are capable of swimming, it is most probable that they reached the island by crossing the Mozambique Channel.
The primitive Artiodactyla thus probably had the typical number (44) of incisor, canine and molar teeth, brachyodont molars, conical odontoid process, four distinct toes on each foot, with metacarpal, metatarsal and all the tarsal bones distinct, and no frontal appendages.
The typical ungulates are the members of the suborders Artiodactyla and Perissodactyla, in both of which the bones of the foot articulate with each other by means of groove-and-tongue joints, whence the name of Diplarthra (equivalent to Ungulata Vera), which has been proposed for these two groups collectively, as distinct from the other representatives of the order.
The Perissodactyla have been brigaded with the Artiodactyla to form the typical group of the ungulates, under the name of Diplarthra, or Ungulata Vera, and the features distinguishing the combined group from the less specialized members of the order Ungulata will be found under the heading of that order.