Class Mammalia Linnaeus, 1758 - mammals
   Subclass Acrotheria Averianov & Lopatin, 2011
     Infraclass Zatheria McKenna, 1975 see Clade Zatheria McKenna 1975
       Superlegion "Prototheria" Gill, 1872 [paraphyletic] see Subclass Prototheria Gill, 1872
         Legion Australosphenida Luo, Cifelli & Kielan-Jaworowska, 2001 see Clade Australosphenida Luo, Cifelli & Kielan-Jaworowska 2001
           1 Order †Ausktribosphenida Rich,Vickers-Rich, Constantine, Flannery, Kool & van Klaveren, 1997 [monotypic]
           2 Order Monotremata Bonaparte, 1837 - monotremes