Edentata (infraclass Eutheria, cohort Unguiculata) An order that comprises two suborders, Palaeanodonta (of ancestral forms), and Xenarthra (the S. American ant-eaters, armadillos, and sloths). The teeth are reduced in number, have a simple peg-like form, and lack enamel; in the ant-eaters they are absent entirely, reflecting adaptation to a diet of invertebrates. The brain case is low, the brain small, the olfactory region large. There are extra articulations between the lumbar vertebrae. The feet have well-developed claws, used for digging or hanging, and some edentates walk on the outsides of the feet. Body temperatures tend to fluctuate widely with ambient air temperature. Edentates are considered to have departed little from the general eutherian form, their superficial features being adaptations to particular ways of life.

Pilosa (order Edentata, suborder Xenarthra) An infra-order that comprises the sloths and ant-eaters, classified as three superfamilies: Megalonychoidea (ground sloths, now extinct); Myrmecophagoidea (ant-eaters); and Bradypodoidea (tree sloths). Members of the Pilosa possess fur and are contrasted with the armadillos of the infra-order Cingulata.