Mammaliaformes Rowe, 1988
   [crown clade] Mammalia Linnaeus, 1758
     Theriiformes Rowe, 1988, new rank
       Holotheria Wible, Rougier, Novacek, McKenna & Dashzeveg, 1995, new rank
         Trechnotheria McKenna, 1975
           Cladotheria McKenna, 1975
             Zatheria [McKenna, 1975]
               Tribosphenida McKenna, 1975:27, new rank
                 [crown clade] Theria Parker & Haswell, 1897:448, new rank
                   Placentalia Owen, 1837:903, new rank
                     Epitheria McKenna, 1975, new rank
                       Preptotheria [McKenna, 1975]
                         Ferae [Linnaeus, 1758]
                           Carnivora [Bowdich, 1821]
                             Caniformia [Kretzoi, 1943]
                               Arctoidea [Flower, 1869]
                                 Ursida [Tedford, 1976]
                                   Phocoidea [Gray, 1821]
                                     Phocidae [Gray, 1821]
                                       Odobeninae [Allen, 1880]
                                         Odobenini [Allen, 1880]
                                           Odobenina Allen, 1880, new rank - walruses
                                             Odobenus [Brisson, 1762]