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 †Notoungulata Roth, 1903
                     Suborder †Toxodontia Owen, 1853
                       1 Family †Oldfieldthomasiidae Simpson, 1945
                       2 Family †Archaeopithecidae Ameghino, 1897
                       3 Family †Isotemnidae Ameghino, 1897
                       4 Family †Homalodotheriidae Gregory, 1910
                       5 Family †Leontiniidae Ameghino, 1895
                       6 Family †Notohippidae Ameghino, 1894
                       7 Family †Toxodontidae Owen, 1845