[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Vertebrata (Lamarck, 1801)
         Branch Craniata Linnaeus, 1758
           Grade Gnathostoma
             Subgrade Pentadactyla lipobranchia
               Branch Amphicondyla [monotypic]
                 Class Mammalia Linnaeus, 1758 - mammals
                   Grade Placentalia Owen, 1837 see Cohort Placentalia Owen, 1837
                     Subclass Ungulata (Linnaeus, 1766)
                       Order Perissodactyla Owen, 1848 - odd-toed ungulates
                         1 Genus Equus Linnaeus, 1758 - horses, zebras, and asses
                         2 Genus Tapirus Brisson, 1762 - tapirs