Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
         Amniota Haeckel, 1866 [Gauthier, Kluge & Rowe 1988] - amniotes
           Class Mammalia Linnaeus, 1758 - mammals
             Subclass Theria Parker & Haswell, 1897
               Theria of Metatherian-Eutherian grade
                 Infraclass Metatheria Huxley, 1880 [monotypic]
                   Order Marsupialia Jameson, 1818 - marsupials see Cohort Marsupialia Jameson, 1818
                     (New World and European marsupials)
                       Suborder Didelphoidea Gray, 1821 see Superfamily Didelphoidea Gray, 1821
                         1 Family Didelphidae Gray, 1821 - American opossums
                         2 Family †Pediomyidae Simpson, 1927
                         3 Family Microbiotheriidae Ameghino, 1887
                         4 Family †Stagodontidae Marsh, 1889
                         5 Family †Borhyaenidae Ameghino, 1894
                         6 Family †Thylacosmilidae Riggs, 1933
                         7 Family †Argyrolagidae xxxAmeghino, 1904