Armadillos, anteaters and sloths are grouped into five families within the mammalian order Xenarthra

The xenarthran time tree shows that armadillos diverged from anteaters and sloths c.70 million years ago (Ma), anteaters and sloths diverging later around c.60 Ma. 

Molecular dating also reveals that the two living genera of sloths diverged c.20 Ma. Molecular dates suggest that the palaeonvironmental changes that occurred during the Cenozoic(66-0 Ma) in South America have influenced the evolutionary history of the Xenarthra (Delsuc & Douzery, 2009).