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]
                         Anagalida [Szalay & McKenna, 1971]
                           Simplicidentata Weber, 1904, new rank
                             Rodentia [Bowdich, 1821]
                               Myomorpha [Brandt, 1855]
                                 Geomorpha Thaler, 1966, new rank
                                   Geomyoidea [Bonaparte, 1845]
                                     Geomyidae [Bonaparte, 1845]
                                       Heteromyinae [Gray, 1868]
                                         Perognathini Coues, 1875, new rank
                                           †Oregonomys [Martin, 1984]