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
                             Subgenus Asinus Gray, 1824 [monotypic] see Equus asinus group Linnaeus, 1758
                               Equus (Asinus) asinus Linnaeus, 1758 - ass
                                 1 Equus (Asinus) asinus africanus Heuglin & Fitzinger, 1866 - wild ass
                                 2 ‡Equus (Asinus) asinus atlanticus P. Thomas, 1884
                                 3 Equus (Asinus) asinus somalicus Sclater, 1885
                                 4 Equus (Asinus) asinus asinus Linnaeus, 1758 - domestic ass