Clade Cynodontia Owen 1861 [Gauthier, Kluge & Rowe 1988]
   Clade Epicynodonts Hopson & Kitching 2001
     Clade Eucynodontia Kemp 1982 [Rowe 1993]
       Clade Mammaliamorpha Rowe 1988
         Class Mammalia Linnaeus, 1758 - mammals
           Clade Yinotheria Chow & Rich 1982 [Kielan-Jaworowska, Cifelli & Luo 2004]
             Subclass Australosphenida Luo, Cifelli & Kielan-Jaworowska, 2001 see Clade Australosphenida Luo, Cifelli & Kielan-Jaworowska 2001
               Order Monotremata Bonaparte, 1837 - monotremes
                 1 ?Family †Kollikodontidae Flannery, Archer, Rich & Jones, 1995
                 2 Family Ornithorhynchidae Gray, 1825 - platypuses
                 3 Family †Steropodontidae Flannery, Archer, Rich & Jones, 1995
                 4 Family Tachyglossidae Gill, 1872 - spiny anteaters