Order †Ornithischia Seeley, 1887
   Parvorder †Genasauria Sereno, 1986 see Clade Genasauria Sereno 1986
     Nanorder †Cerapoda Sereno, 1986 see Suborder Cerapoda Sereno, 1986
       Hypoorder †Marginocephalia Sereno, 1986 see Clade Marginocephalia Sereno 1986
         Suborder †Ceratopsia Marsh, 1890 see Infraorder Ceratopsia Marsh, 1890
           Infraorder †Neoceratopsia Sereno, 1986 see Clade Neoceratopsia Sereno 1986
             Microorder †Coronosauria Sereno, 1986 see Clade Neoceratopsia Sereno 1986
               Genus †Protoceratops Granger & Gregory, 1923