Edentata

Edentata

A group of mammals that encompasses several orders of unusual fossil and living animals characterized by reduced or strongly modified teeth. Usually included in this group are the order Pholidota, the pangolins or scaly anteaters of Africa and Southeast Asia; the order Xenarthra, the true anteaters, armadillos, sloths, and their relatives derived mainly from South and Central America; and the extinct Palaeanodonta, an early Cenozoic group of burrowing mammals from North America. The term “edentate” means toothless. Historically a wide range of toothless mammals and mammals with reduced dentition have been incorporated in this taxonomic group, among them aardvarks and echidnas. Modern systematists restrict the term to pholidotans, xenarthrans, and palaeanodonts based on several shared anatomical specializations found exclusively in these three taxa. Only the pangolins and the true anteaters lack teeth entirely, but all edentates are characterized by a reduced dentition. Typically the incisor teeth are lacking, the tooth enamel is strongly reduced or absent (although enamel is retained in a few of the early fossil forms and in the embryos of living armadillos), and tooth replacement is lost. All three groups share digging adaptations, and specializations for feeding on ants and termites. In addition, pangolins and some xenarthrans have a scaly external body covering. Some mammalian systematists have suggested that edentates represent one of the most primitive groups of living placental mammals, although the matter is somewhat controversial. See Tooth