Order †Pachycephalosauria Maryañska & Osmólska, 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974
Count: -
   Family †Pachycephalosauridae Sternberg, 1945
  Count: [†*] †14g;18s
     Genus †Gravitholus Wall & Galton, 1979, nom. dub.
    Count: [†*] †1s
       †Gravitholus albertae Wall & Galton, 1979, nom. dub.
      Count: -