Phylum [Vertebrata] Lamarck, 1801 see Infraphylum Vertebrata Lamarck, 1801
   Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theria Parker & Haswell, 1897
       Infraclass Eutheria Gill, 1872
         Cohort Epitheria McKenna, 1975
           Superorder Tethytheria McKenna, 1975
             Order Sirenia Gill, 1872 - sea cows
               Family †Prorastomidae Cope, 1889
                 1 Genus †Prorastomus Owen, 1855