Mammaliaformes Rowe 1988
   [crown] Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theriiformes Rowe, 1988 see Division Theriiformes Rowe, 1988
       Infraclass †Allotheria Marsh, 1880 see Clade Allotheria Marsh 1880
         Order †Multituberculata Cope, 1884
           Suborder †Cimolodonta McKenna, 1975
             Superfamily †Taeniolabidoidea Granger & Simpson, 1929
               Family †Eucosmodontidae Jepsen, 1940
                 Subfamily †Eucosmodontinae Jepsen, 1940 see Family Eucosmodontidae Jepsen, 1940
                   Tribe †Eucosmodontini Jepsen, 1940 see Family Eucosmodontidae Jepsen, 1940
                     Genus †Stygimys Sloan & Van Valen, 1965