Phylum Chordata Bateson, 1885 - chordates
   Subphylum Vertebrata Cuvier, 1812 - vertebrates
     Class Mammalia Linnaeus, 1758 - mammals
       Order Artiodactyla Owen, 1848 - even-toed ungulates see Order Cetartiodactyla Montgelard, Catzeflis & Douzery, 1997
         Family †Agriochoeridae Leidy, 1869
         Family †Amphimerycidae Stehlin, 1910
         Family †Anoplotheriidae Gray, 1821
         Family †Anthracotheriidae Leidy, 1869
         Family Bovidae Gray, 1821 - antelope, cattle, bison, buffalo, goats, and sheep
         Family †Cainotheriidae Cope, 1881
         Family Camelidae Gray, 1821 - camels, guanaco, llama, alpaca, and vicuña
         Family †Cebochoeridae Lydekker, 1883
         Family Cervidae Batsch, 1788 - deer
         Family †Choeropotamidae Owen, 1845
         Family †Dichobunidae Turner, 1849
         Family †Entelodontidae Lydekker, 1883
         Family †Gelocidae Schlosser, 1886
         Family Giraffidae Gray, 1821 - okapi and giraffe
         Family †Haplobunodontidae Pilgrim, 1941 see Family Choeropotamidae Owen, 1845
         Family †Helohyidae Marsh, 1877
         Family Hippopotamidae Gray, 1821 - hippopotamuses
         Family †Hoplitomerycidae Leinders, 1983
         Family †Hypertragulidae Cope, 1879
         Family †Leptochoeridae Marsh, 1894 see Subfamily Leptochoerinae Marsh, 1894
         Family †Leptomerycidae Zittel, 1893
         Family †Merycoidodontidae Hay, 1902 see Subfamily Oreodontinae Leidy, 1869
         Family †Oromerycidae Gazin, 1955
         Family †Palaeomerycidae Lydekker, 1883
         Family †Protoceratidae Marsh, 1891
         Family Suidae Gray, 1821 - pigs
         Family Tayassuidae Palmer, 1897 (1849) - peccaries
         Family Tragulidae Milne-Edwards, 1864 - chevrotains
         Family †Xiphodontidae Flower, 1884