Order †Pachycephalosauria Maryañska & Osmólska, 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974
   Family †Pachycephalosauridae Sternberg, 1945
     Genus †Sphaerotholus Williamson & Carr, 2002 see Genus Prenocephale Maryañska & Osmólska, 1974
       1 †Sphaerotholus buchholtzae T.E. Williamson & T.D. Carr, 2002 see Prenocephale edmontonensis (Brown & Schlaikjer, 1943) R.M. Sullivan, 2000
       2 †Sphaerotholus goodwini T.E. Williamson & T.D. Carr, 2002 see Prenocephale goodwini (T.E. Williamson & T.D. Carr, 2002) R.M. Sullivan, 2003