Phylum [Vertebrata] Lamarck, 1801 see Infraphylum Vertebrata Lamarck, 1801
   Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theria Parker & Haswell, 1897
       Infraclass Metatheria Huxley, 1880
         Order Marsupialia Jameson, 1818 - marsupials see Cohort Marsupialia Jameson, 1818
           Suborder Didelphoidea Gray, 1821 see Superfamily Didelphoidea Gray, 1821
             1 Family Didelphidae Gray, 1821 - American opossums
             2 Family †Borhyaenidae Ameghino, 1894
             3 Family †Thylacosmilidae Riggs, 1933
             4 Family †Argyrolagidae Ameghino, 1904
             5 Family †Necrolestidae Ameghino, 1894