Phylum [Vertebrata] (Lamarck, 1801)
   Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theria Parker & Haswell, 1897
       Infraclass Eutheria Gill, 1872
         Cohort Epitheria McKenna, 1975
           Superorder Ungulata Linnaeus, 1766
             Order †Tillodontia Marsh, 1875
               Family †Esthonychidae Cope, 1883 see Family Tillotheriidae Marsh, 1875
                 Genus †Trogosus Leidy, 1871