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
                 1 Family †Aegialodontidae Kermack, 1967
                 2 Family †Deltatheridiidae Gregory & Simpson, 1926
                 3 Infraclass Metatheria Huxley, 1880 [monotypic]
                 4 Infraclass Eutheria Gill, 1872