EDENTATA, e-den-ti'ta one of the smaller orders of mammals, most of which are found in South America. It includes the South America' sloths, ant-eaters and armadillos, and two Old World groups, all of which are char acterized by an absence of front teeth, and in a few instances by completely toothless jaws, whence the generic name. Where teeth are present they are without enamel, and lack dis tinct roots, are all alike and generally are not preceded by a set of milk teeth. These animals are ranked comparatively low in the scale of mammals, not only on account of their defi ciency in teeth, but also because their brains are relatively small and lack the convolution charac teristic of the more highly developed orders. With two exceptions, the armadillos and pan golins, the Edentata are clothed with coarse hair, and they never are completely hairless. The armadillos are peculiar among mammals, in that their bodies are covered with an armor of bony plate ; and in the pangolins the entire body is protected by a coat of overlapping, horny scales. The typical edentates are the sloths (Brodypodida), the ant-eaters (Myrmeco phagida) and tlie armadillos (Dasypodida), all of which are American; the two groups in the order, native to Africa and Asia, are the pan golins (Squamata) and the aardvarks (Tukli dentata), although Lydekker questions the cor rectness of placing the last two among the edentates, preferring to consider the present and extinct forms as an entirely American order. The sloths live on vegetable food ex clusively, the other group chiefly on insects or animal matter softened by decay.
Fossil Edentates.— Of the large and nu merous edentate fauna which lived in South American during the Tertiary and Quaternary periods, some (Mylodon, Megaionyx, Glypto don) spread to North America during the Pliocene and Pleistocene epochs; the armadillo is still found as far north as the Mexican bor der of the United States. Their earliest an cestors were, perhaps, North American, but their development was exclusively in the south ern continent during most of the Tertiary period. The earlier stages in their evolution were less divergent from the normal mammals than the present edentates, and were of small or moderate size; later on they became of huge size and very highly specialized. The most remark able among them were the Megatherida, ground-sloths, distantly related to the modern ant-eaters and true sloths, but terrestrial animals, very heavily proportioned, with massive hind quarters and tail, and immense digging claws; and the Glyptodonts, related to armadillos but much larger, with massive unjointed carapace like that of a tortoise and with hoofs instead of claws. Besides these were numerous true armadillos, both large and small, some ancestral to the modern species, others of extinct races. No fossil ant-eaters have yet been discovered, and fossil tree-sloths are almost equally un known; but the fossil beds of South America have been so imperfectly explored that this fact is not surprising. See AARD-VARK; ANTEATER; ARMADILLO ; GANODONTA ; GLYPTODON ; MANIS ; MEGATHERIUM ; MYLODON ; SLOTH.