Class Mammalia Linnaeus, 1758 - mammals
   Subclass Boreosphenida Luo, Cifelli & Kielan-Jaworowska, 2001 - tribotherians see Clade Boreosphenida Luo, Cifelli & Kielan-Jaworowska 2001
     Infraclass Metatheria Huxley, 1880
       1 Order †Deltatheroida Kielan-Jaworowska, 1982
       2 Order †Asiadelphia Trofimov & Szalay, 1993
       3 Cohort Marsupialia Jameson, 1818 - marsupials