Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
         Amniota Haeckel, 1866 [Gauthier, Kluge & Rowe 1988] - amniotes
           Class Mammalia Linnaeus, 1758 - mammals
             Subclass Theria Parker & Haswell, 1897
               Theria of Metatherian-Eutherian grade
                 Infraclass Eutheria Gill, 1872
                   Order Xenarthra Cope, 1889 - xenarthrans see Magnorder Xenarthra Cope, 1889
                     Infraorder Pilosa Flower, 1883 - sloths see Order Pilosa Flower, 1883
                       Superfamily Megalonychoidea
                         1 Family Megalonychidae Gervais, 1855 - West Indian sloths and two-toed tree sloths
                         2 Family ‡Megatheriidae Gray, 1821