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 Anagalida (Szalay & McKenna, 1971) McKenna, 1975 see Order Anagalida Szalay & McKenna, 1971
                           Mirorder Simplicidentata Weber, 1904
                             Order Rodentia Bowdich, 1821 - rodents
                               Suborder Hystricognatha Woods, 1976
                                 Infraorder Hystricognathi Tullberg, 1899
                                   Parvorder Caviida Bryant & McKenna, 1995
                                     Superfamily Octodontoidea (Waterhouse, 1839) Simpson, 1945
                                       Family Octodontidae Waterhouse, 1839 - octodonts
                                         Subfamily Octodontinae (Waterhouse, 1839) M.C. McKenna & S.K. Bell, 1997
                                           Tribe Ctenomyini (Lesson, 1842) M.C. McKenna & S.K. Bell, 1997 - tuco-tucos
                                             1 Genus †Palaeoctodon Rovereto, 1914
                                             2 Genus †Xenodontomys Kraglievich, 1927
                                             3 Genus †Eucoelophorus Ameghino, 1909
                                             4 Genus Ctenomys de Blainville, 1826 - tuco-tucos
                                             5 Genus †Praectenomys Villarroel, 1975
                                             6 Genus †Actenomys Burmeister, 1888
                                             7 Genus †Megactenomys Rusconi, 1930