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 Artiodactyla Owen, 1848 - even-toed ungulates see Order Cetartiodactyla Montgelard, Catzeflis & Douzery, 1997
                     Suborder Tylopoda "Illiger, 1811"
                       1 Superfamily †Merycoidodontoidea Hay, 1902 see Superfamily Oreodontoidea Leidy, 1869
                       2 Superfamily †Anoplotheroidea Gray, 1821 see Superfamily Anoplotherioidea Gray, 1821
                       3 Superfamily Cameloidea Gray, 1821
                       4 Family †Xiphodontidae Flower, 1884
                       5 Family †Amphimerycidae Stehlin, 1910
                       6 Family †Protoceratidae Marsh, 1891