Kingdom [Animalia] Linnaeus, 1758 - animals
   Subkingdom Metazoa Haeckel, 1874 see Kingdom Animalia Linnaeus, 1758
     Division Eumetazoa Butschli, 1910 see Subkingdom Eumetazoa Butschli, 1910
       Subdivision Bilateralia
         Phylum Chordata Bateson, 1885 - chordates
           Subphylum Vertebrata Cuvier, 1812 - vertebrates
             Class Mammalia Linnaeus, 1758 - mammals
               Subclass Eutheria Gill, 1872 see Infraclass Eutheria Gill, 1872
                 Superorder Mesaxonia (Marsh, 1884)
                   Order Perissodactyla Owen, 1848 - odd-toed ungulates
                     Suborder Hippomorpha Wood, 1937
                       Superfamily Equoidea (Gray, 1821) Hay, 1902 see Family Equidae Gray, 1821
                         Family Equidae Gray, 1821 - horses, zebras, and asses
                           Genus Equus Linnaeus, 1758 - horses, zebras, and asses
                             1 Subgenus Hippotigris Smith, 1841 see Equus zebra group Linnaeus, 1758
                             2 Subgenus Dolichohippus Heller, 1912 [monotypic] see Equus grevyi group Oustalet, 1882
                             3 Subgenus Asinus Gray, 1824 [monotypic] see Equus asinus group Linnaeus, 1758
                             4 Subgenus Hemionus Stehlin & Graziosi, 1935 see Equus hemionus group Pallas, 1775
                             5 Subgenus Equus Linnaeus, 1758 see Equus caballus group Linnaeus, 1758