Phylum [Vertebrata] Lamarck, 1801 see Infraphylum Vertebrata Lamarck, 1801
   Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theria Parker & Haswell, 1897
       Infraclass Eutheria Gill, 1872
         Cohort Epitheria McKenna, 1975
           Superorder Ungulata Linnaeus, 1766
             Order Perissodactyla Owen, 1848 - odd-toed ungulates
               Suborder Hippomorpha Wood, 1937
                 1 Family †Palaeotheriidae Bonaparte, 1850
                 2 Family Equidae Gray, 1821 - horses, zebras, and asses
                 3 Family †Brontotheriidae Marsh, 1873