Order †Pachycephalosauria Maryañska & Osmólska, 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974 Family †Pachycephalosauridae Sternberg, 1945 Genus †Gravitholus Wall & Galton, 1979, nom. dub. 1 †Gravitholus albertae Wall & Galton, 1979, nom. dub.