Clade Mammaliaformes Rowe 1988 [Rowe 1988]
   [crown] Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theriiformes (Rowe, 1988) M.C. McKenna & S.K. Bell, 1997 see Division Theriiformes
       Infraclass Holotheria (Wible et al., 1995) M.C. McKenna & S.K. Bell, 1997 see [unranked] Holotheria
         Superlegion Trechnotheria McKenna, 1975 see [unranked] Trechnotheria McKenna, 1975
           Legion Cladotheria McKenna, 1975 see [unranked] Cladotheria McKenna, 1975
             Sublegion Zatheria McKenna, 1975 see [unranked] Zatheria McKenna, 1975
               Infralegion Tribosphenida McKenna, 1975 see Sublegion Boreosphenida
                 Supercohort Theria (Parker & Haswell, 1897) M.C. McKenna & S.K. Bell, 1997 - therians see [unranked] Theria
                   Cohort Placentalia (Owen, 1837) M.C. McKenna & S.K. Bell, 1997 - placentals
                     Magnorder Epitheria (McKenna, 1975) M.C. McKenna & S.K. Bell, 1997 see Cohort Placentalia (Owen, 1837) M.C. McKenna & S.K. Bell, 1997
                       Superorder Preptotheria (McKenna, 1975) McKenna, 1993
                         Grandorder Ferae (Linnaeus, 1758) McKenna, 1975 see Superorder Ferae (Linnaeus, 1758) Simpson, 1945
                           Order Carnivora Bowdich, 1821 - carnivores
                             Suborder Caniformia Kretzoi, 1943
                               Infraorder Arctoidea Flower, 1869
                                 Parvorder Ursida Tedford, 1976
                                   Superfamily Phocoidea (Gray, 1821) Smirnov, 1908
                                     Family Phocidae Gray, 1821 - true seals
                                       Subfamily Odobeninae (Allen, 1880) Mitchell, 1968
                                         Tribe Odobenini (Allen, 1880) Deméré, 1994
                                           Subtribe Odobenina (Allen, 1880) R.H. Tedford, in M.C. McKenna & S.K. Bell, 1997
                                             Genus †Alachtherium Du Bus, 1867