Class Mammalia Linnaeus, 1758 - mammals
   Subclass Prototheria Gill, 1872 - monotremes
     Infraclass Ornithodelphia (de Blainville, 1834) see Subclass Prototheria Gill, 1872
       1 Order Monotremata Bonaparte, 1837 - monotremes
       2 Order †Multituberculata Cope, 1884