Mammaliaformes Rowe 1988
   [crown] Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theriiformes Rowe, 1988 see Division Theriiformes Rowe, 1988
       Infraclass Holotheria Wible, Rougier, Novacek, McKenna & Dashzeveg, 1995 see Clade Holotheria Wible, Rougier, Novacek, McKenna & Dashzeveg 1995
         Superlegion Trechnotheria McKenna, 1975 see Clade Trechnotheria McKenna 1975
           Legion Cladotheria McKenna, 1975 see Clade Cladotheria McKenna 1975
             Sublegion Zatheria McKenna, 1975 see Clade Zatheria McKenna 1975
               Infralegion Tribosphenida McKenna, 1975 see Subclass Boreosphenida Luo, Cifelli & Kielan-Jaworowska, 2001
                 [crown] Supercohort Theria Parker & Haswell, 1897 - therians see Subclass Theria Parker & Haswell, 1897
                   Cohort Placentalia Owen, 1837 - placentals
                     Magnorder Epitheria McKenna, 1975 see Cohort Placentalia Owen, 1837
                       Superorder Preptotheria McKenna, 1975
                         Grandorder Ungulata Linnaeus, 1766
                           Mirorder Altungulata Prothero & Schoch, 1989
                             Order Uranotheria McKenna & Bell, 1997 see Grandorder Paenungulata Simpson, 1945
                               Suborder Tethytheria McKenna, 1975 see Mirorder Tethytheria McKenna, 1975
                                 Infraorder Sirenia Gill, 1872 - manatees, dugong, and sea cow see Order Sirenia Gill, 1872
                                   Family Dugongidae Gray, 1821 - dugong and sea cow
                                     Subfamily †Rytiodontinae Abel, 1914
                                       Genus †Xenosiren Domning, 1989