Dinosauria Owen 1841 †Ornithischia Seeley 1887 see Order Ornithischia Seeley, 1887 †Genasauria Sereno 1986 †Neornithischia Cooper 1985 †Marginocephalia Sereno 1986 †Pachycephalosauria Maryañska & Osmólska 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974 1 Genus †Stenopelix Meyer, 1857 2.1 Genus †Goyocephale Perle, Maryanska & Osmólska, 1982 2.2.1 Genus †Homalocephale Maryañska & Osmólska, 1974 2.2.2 †Pachycephalosauridae Sternberg 1945 see Family Pachycephalosauridae Sternberg, 1945