Order †Pachycephalosauria Maryañska & Osmólska, 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974 Family †Pachycephalosauridae Sternberg, 1945 †Pachycephalosaurini Sullivan, 2003 Genus †Stenotholus Giffin, Gabriel & Johnson, 1988 see Genus Pachycephalosaurus Brown & Schlaikjer, 1943 †Stenotholus kohleri Giffin et al., 1987 see Stygimoloch spinifer Galton & Sues, 1983