Open Paleo

Pachycephalosaurinae

Sternberg, 1945 Type genus Pachycephalosaurus

Its genera lived 93.9–66.0 million years ago Late Cretaceous
Late Cretaceous stages

Pachycephalosaurinae is the derived subfamily of pachycephalosaurid dinosaurs, encompassing the dome-headed members of the group that are more closely related to Pachycephalosaurus than to the earlier-branching Stegoceras. Its members were small, bipedal, plant-eating ornithischians known from the Cretaceous of North America and Asia, distinguished by a thickened skull roof formed from the fused and greatly enlarged frontal and parietal bones. Alongside the classic high-domed forms, the subfamily also takes in several flatter-skulled taxa that fall on the Pachycephalosaurus side of the family tree, some of which may represent juveniles or females of domed species. The heavily ossified skulls are typically ornamented with blunt horns and nodes around their margins, and the domes themselves have often been interpreted as weapons used in intraspecific head- or flank-butting.

Diagnosis

  1. Fully domed frontoparietal (sensu Sereno, 1998)
  2. Supratemporal fenestrae closed in adults
  3. Parietosquamosal contact positioned caudodorsal to the occiput
  4. Epaxial muscle scars restricted to a position dorsolateral to the foramen magnum

Genera placed directly in Pachycephalosaurinae

  • Acrotholus Evans et al., 2013 Santonian (85.7–83.6 Ma)Canada
  • Alaskacephale Sullivan, 2006 Maastrichtian (72.2–66.0 Ma)United States
  • Brontotholus Woodruff et al., 2025 Campanian (83.6–72.2 Ma)United States
  • Foraminacephale Schott & Evans, 2016 Campanian (83.6–72.2 Ma)Canada
  • Goyocephale Perle et al., 1982 Santonian–Maastrichtian (85.7–66.0 Ma)Mongolia
  • Homalocephale Maryańska & Osmólska, 1974 Maastrichtian (72.2–66.0 Ma)Mongoliaunder dispute
  • Pachycephalosaurus Brown & Schlaikjer, 1943 Maastrichtian (72.2–66.0 Ma)United States
  • Platytholus Horner et al., 2022 Maastrichtian (72.2–66.0 Ma)United States
  • Prenocephale Maryańska & Osmólska, 1974 Maastrichtian (72.2–66.0 Ma)Mongolia
  • Sinocephale Evans et al., 2021 Turonian–Santonian (93.9–83.6 Ma)China
  • Sphaerotholus Williamson & Carr, 2003 Campanian (83.6–72.2 Ma)United States
  • Tylocephale Maryańska & Osmólska, 1974 Campanian (83.6–72.2 Ma)Mongolia

References

  1. Sternberg, C. M. (1945). Pachycephalosauridae proposed for dome-headed dinosaurs, Stegoceras lambei, n. sp., described. Journal of Paleontology 19.

    Named Pachycephalosauridae; Pachycephalosaurinae dates from this work by ICZN coordination.

    sternberg1945a
  2. Madzia, D.; Arbour, V. M.; Boyd, C. A.; Farke, A. A.; Cruzado-Caballero, P.; Evans, D. C. (2021). The phylogenetic nomenclature of ornithischian dinosaurs. PeerJ 9: e12362. doi:10.7717/peerj.12362

    Defined Pachycephalosaurinae as the largest clade containing Pachycephalosaurus wyomingensis but not Stegoceras validum.

    madzia2021a
  3. Williamson, T. E.; Carr, T. D. (2003). A new genus of derived pachycephalosaurian from western North America. Journal of Vertebrate Paleontology 22(4): 779-801. Informa UK Limited. doi:10.1671/0272-4634(2002)022[0779:angodp]2.0.co;2

    Recovered Pachycephalosaurinae under Sereno's definition, with node synapomorphies shown in its cladogram.

    williamson2003a
  4. Sereno, P. C. (1998). A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 210: 41-83. doi:10.1127/njgpa/210/1998/41

    Defined Pachycephalosaurinae as pachycephalosaurids closer to Pachycephalosaurus than to Stegoceras, crediting the name to Sternberg (1945).

    sereno1998a