Temporal range: Late Cretaceous, 80 Ma
Maryanska & Osmolska, 1974
Maryanska & Osmolska, 1974
Homalocephale (from Greek ωμαλος, homalos, "even", and κεφαλή, kephalē, "head") is a genus of dinosaur belonging to the pachycephalosaurid family, which lived during the late Cretaceous period of what is now Mongolia, 80 million years ago. The genus was described in 1974 by Osmólska & Maryañska, and consists of a single species, H. calathocercos, though this may be a synonym (and juvenile form) of Prenocephale. Homalocephale was 1.8 metres (6 ft) long and herbivorous.
Unlike other definitely adult pachycephalosaurs (though similar to probable juvenile specimens referred to Dracorex and Goyocephale), Homalocephale sported a flat, wedge-shaped skull roof. Nonetheless, the surface of the skull was fairly thickened.
The species is also noted for having an unusually broad pelvis, which lead some paleontologists to suggest that the wide hips were for giving birth to live young. Others have suggested that the width served to protect vital organs from harm during flank-butting. Homalocephale also had rather long legs, indicating a fast-moving gait.
The type species, H. calathocercos, was described from an incomplete skull and postcranial material. The specimen has large openings on the top of the skull, a distinct frontoparietal suture, low and long infratemporal fenestrae, and a large, round eye socket. The forehead is notably rough, with multiple nodules on the lateral and posterior sides of the squamosal bone. Palaeontologists concluded that the specimen was an adult, despite the fact that the sutures are discernible and that it had a flat skull (a juvenile trait in many pachycephalosaurid species). In 2010, a study by Nick Longrich and colleagues suggested that flat-headed pachycephalosaurs were just juvenile forms of dome-headed adults, a view also supported by the earlier analysis of Horner and Goodwin in 2009. Longrich and colleagues suggested that Homalocephale is actually the juvenile or sub-adult stage of Prenocephale.
- Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
- Maryańska, Teresa; Chapman, Ralph E.; Weishampel, David B. (2004). "Pachycephalosauria". In Weishampel, David B.; Dodson, Peter; Osmólska Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 464–477. ISBN 0-520-24209-2.
- Carpenter, Kenneth (1997). "Agonistic behavior in pachycephalosaurs (Ornithischia:Dinosauria): a new look at head-butting behavior". Contributions to Geology. 32 (1): 19–25.
- Longrich, N.R., Sankey, J. and Tanke, D. (2010). "Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA." Cretaceous Research, . doi:10.1016/j.cretres.2009.12.002
- Fantastic Facts About Dinosaurs (ISBN 0-7525-3166-2)