[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 Carnaria
                       Order Pinnipedia Illiger, 1811 - seals, sea lions, and walrus see Parvorder Pinnipedia Illiger, 1811
                         Genus Trichecus Müller, 1773 see Genus Trichechus Linnaeus, 1758