Class Mammalia Linnaeus, 1758 - mammals
   Subclass Theria Parker & Haswell, 1897
     Infraclass Eutheria Gill, 1872
       Cohort Ferungulata
         Superorder Mesaxonia (Marsh, 1884)
           Order Perissodactyla Owen, 1848 - odd-toed ungulates
             Suborder Hippomorpha Wood, 1937
               Family Equidae Gray, 1821 - horses, zebras, and asses