Mammaliaformes Rowe 1988, nom. cl. inval. see Clade Mammaliaformes Rowe 1988 [Rowe 2020]
   [crown] Class Mammalia Linnaeus, 1758 - mammals
     Subclass Prototheria Gill, 1872 - monotremes
       Order Platypoda Gill, 1872 - platypuses see Order Monotremata Bonaparte, 1837
         Family Ornithorhynchidae Gray, 1825 - platypuses
           1 Genus †Steropodon Archer, Flannery, Ritchie & Molnar, 1985
           2 Genus †Monotrematum Pascual, Archer, Ortiz Jaureguizar, Prado, Godthelp & Hand, 1992
           3 Genus †Obdurodon Woodburne & Tedford, 1975
           4 Genus Ornithorhynchus Blumenbach, 1800 - duck-billed platypus