Class Reptilia Linnaeus, 1758 - reptiles
   Subclass Archosauria Cope, 1869 see Division Archosauria Cope, 1869
     Order †Ornithischia Seeley, 1887
       Suborder †Ceratopsia Marsh, 1890 see Infraorder Ceratopsia Marsh, 1890
         1 Family †Protoderatopsidae see Family Protoceratopsidae Granger & Gregory, 1923
         2 Family †Ceratopsidae Marsh, 1888
         3 Family †Pachyrhinosauridae Sternberg, 1950
         4 Family †Caenagnathidae Sternberg, 1940