AMBLYPODA, an extinct order of hoofed mammals. They inhabited North America, Europe and Asia during the early part of the Tertiary period and were the largest quadrupeds of their time. The limbs and feet were like those of elephants, long, straight, postlike legs with short, rounded, five-toed feet, small hoofs with heavy elastic pads to support the weight of the animal. The skull was massive with short-crowned cheek teeth of a peculiar lophiodont or cross-crested pattern and enlarged canine tusks which, in one group, suggest those of pigs, in another those of the tusked deer. These tusks had no likeness to the incisor tusks of elephants. The brain was small.
Although they resembled the elephants in the general character of the limbs, the structure of wrist and ankle bones precludes any near relationship; moreover the characters of skull and teeth were quite peculiar. The Amblypoda appear to have evolved from primitive ancestors related to the Condylarthra, and are connected with them through a number of intermediate types of Palaeocene mammals. Coryphodon of the Lower Eocene (Europe and North America) was about the size of the larger bears. The front teeth were enlarged ; the stout flaring tusks and heavy muzzle suggesting the hippopotamus; the skull broad-topped and roughened ; the proportions of the body much as in the bears; the tail rather small. The premolar teeth had crescentic cusps; the true molars a combination of crescents and curving crests of unique pattern.
The Uintatheres or Dinocerata of North America were the most specialized and largest of the Amblypoda. In these the upper in cisors were absent ; the upper canines enlarged into great dagger like tusks; the cheek teeth small with a distinctive pattern of crescents and crests; and the top of the skull bore two or three pairs of stout prominent bony bosses or "horns" analpgous to the horns of the giraffe. This group first appears in the Palaeocene of North America and Central Asia with small ancestral types no larger than a pig—hornless; but already showing the character istic pattern of tusks and cheek teeth.
Bathyopsis of the Lower Eocene was somewhat larger; still hornless; but with rudimentary bosses on the skull. Uintatherium (Dinoceras) of the Middle Eocene had two pairs of horns, one over the orbits, the other near the back of the skull. It was as large as a small rhinoceros. Eobasileus (Loxolophiodon) of the Upper Eocene had a third pair of horns above the nasals, and the size of the two other pairs increased. This animal attained the size of the largest rhinoceros. The brain remained quite un developed, very small in contrast to the huge massive skull.
(See PALAEONTOLOGY.) (W. D. M.)