Southern three-banded armadillo, Tolypeutes matacus Brazilian three-banded armadillo, Tolypeutes tricinctus Pichi or dwarf armadillo, Zaedyus pichiy Subfamily †Glyptodontinae: glyptodonts Family Dasypodidae: long-nosed armadillos Nine-banded armadillo or long-nosed armadillo, Dasypus novemcinctus Seven-banded armadillo, Dasypus septemcinctus Southern long-nosed armadillo, Dasypus hybridus Llanos long-nosed armadillo, Dasypus sabanicola Great long-nosed armadillo, Dasypus kappleri Hairy long-nosed armadillo, Dasypus pilosus Yepes's mulita, Dasypus yepesi Family †Pampatheriidae: pampatheres Order Pilosa Suborder Folivora: sloths Family Bradypodidae: three-toed sloths Pygmy three-toed sloth, Bradypus pygmaeus Brown-throated three-toed sloth, Bradypus variegatus Pale-throated three-toed sloth, Bradypus tridactylus Maned three-toed sloth, Bradypus torquatus Family †Megalonychidae: megalonychid ground sloths Family †Megatheriidae: megatheriid ground sloths Family †Nothrotheriidae: nothrotheriid ground sloths and aquatic sloths Family Choloepodidae: two-toed sloths Hoffman's two-toed sloth, Choloepus hoffmanni Linnaeus's two-toed sloth or southern two-toed sloth, Choloepus didactylus Family †Mylodontidae: mylodontid ground sloths Suborder Vermilingua: anteaters Family Cyclopedidae: silky anteaters Silky anteater, Cyclopes didactylus Family Myrmecophagidae: anteaters Giant anteater, Myrmecophaga tridactyla Northern tamandua, Tamandua mexicana Southern tamandua, Tamandua tetradactyla Characteristics Xenarthrans share several characteristics not present in other mammals. Authorities have tended to agree they are a primitive group of placental mammals not very closely related to other orders, without agreeing on how to classify them. George Gaylord Simpson first suggested in 1931 that their combination of unique characteristics shows the group evolved from highly specialized early ancestors that lived underground or were nocturnal and dug with their forelimbs to feed on social insects like ants or termites. Most researchers since then have agreed. These extreme characteristics led to their confusion with unrelated groups that had similar specializations (aardvarks and pangolins), and obscures their relationships with other mammals. Dentition The teeth of xenarthrans differ from all other mammals. The dentition of most species is either significantly reduced and highly modified, or absent. With the single exception of Dasypus armadillos and their ancestral genus Propraopus, xenarthrans do not have a milk dentition. They have a single set of teeth through their lives; these teeth have no functional enamel, and usually there are few or no teeth in the front of the mouth and the rear teeth all look alike. As a result, it is impossible to define Xenarthra as having incisors, canines, premolars, or molars. Since most mammals are classified by their teeth, it has been difficult to determine their relationships to other mammals. Xenarthrans may have evolved from ancestors that had already lost basic mammalian dental features like tooth enamel and a