Mammaliaformes Rowe 1988
   [crown] Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theriiformes Rowe, 1988 see Division Theriiformes Rowe, 1988
       Infraclass Holotheria Wible, Rougier, Novacek, McKenna & Dashzeveg, 1995 see Clade Holotheria Wible, Rougier, Novacek, McKenna & Dashzeveg 1995
         Superlegion Trechnotheria McKenna, 1975 see Clade Trechnotheria McKenna 1975
           Legion Cladotheria McKenna, 1975 see Clade Cladotheria McKenna 1975
             Sublegion Zatheria McKenna, 1975 see Clade Zatheria McKenna 1975
               Infralegion Tribosphenida McKenna, 1975 see Subclass Boreosphenida Luo, Cifelli & Kielan-Jaworowska, 2001
                 [crown] Supercohort Theria Parker & Haswell, 1897 - therians see Subclass Theria Parker & Haswell, 1897
                   Cohort Placentalia Owen, 1837 - placentals
                     Magnorder Epitheria McKenna, 1975 see Cohort Placentalia Owen, 1837
                       Superorder Preptotheria McKenna, 1975
                         Grandorder Ferae Linnaeus, 1758
                           Order Carnivora Bowdich, 1821 - carnivores
                             Suborder Caniformia Kretzoi, 1943
                               Infraorder Arctoidea Flower, 1869
                                 Parvorder Ursida Tedford, 1976
                                   Superfamily Phocoidea Gray, 1821
                                     Family Phocidae Gray, 1821 - true seals
                                       Subfamily Odobeninae Allen, 1880
                                         Tribe Odobenini Allen, 1880
                                           Subtribe Odobenina Allen, 1880 - walruses see Tribe Odobenini Allen, 1880
                                             Genus Odobenus Brisson, 1762 - walrus