Order †Pachycephalosauria Maryañska & Osmólska, 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974
   Family †Pachycephalosauridae Sternberg, 1945
     †Pachycephalosaurini Sullivan, 2003
       Genus †Pachycephalosaurus Brown & Schlaikjer, 1943
         1 †Pachycephalosaurus wyomingensis (Gilmore, 1931) Brown & Schlaikjer, 1943
         1.0.1 †Pachycephalosaurus grangeri Brown & Schlaikjer, 1943 see Pachycephalosaurus wyomingensis (Gilmore, 1931) Brown & Schlaikjer, 1943
         1.0.2 †Pachycephalosaurus reinheimeri Brown & Schlaikjer, 1943 see Pachycephalosaurus wyomingensis (Gilmore, 1931) Brown & Schlaikjer, 1943