Class Mammalia Linnaeus, 1758 - mammals
   Subclass †Allotheria Marsh, 1880
     Order †Multituberculata Cope, 1884
       Suborder †Cimolodonta McKenna, 1975
         Family †Eucosmodontidae Jepsen, 1940, incertae sedis
           Genus †Stygimys Sloan & Van Valen, 1965
             1 †Stygimys kuszmauliᵀ Sloan & Van Valen, 1965
             2 †Stygimys cupressus Fox, 1989