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 Anagalida Szalay & McKenna, 1971 see Order Anagalida Szalay & McKenna, 1971
                           Mirorder Simplicidentata Weber, 1904
                             Order Rodentia Bowdich, 1821 - rodents
                               Suborder Hystricognatha Woods, 1976 see Suborder Hystricomorpha Brandt, 1855
                                 Infraorder Hystricognathi Tullberg, 1899
                                   Parvorder Caviida Bryant & McKenna, 1995 see Parvorder Caviomorpha Wood & Patterson, 1955
                                     Superfamily Cavioidea Fischer de Waldheim, 1817
                                       Family Hydrochoeridae Gray, 1825
                                         Subfamily Hydrochoerinae Gray, 1825
                                           Genus †Chapalmatherium Ameghino, 1908