Homalocephale

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. The genus was described in 1974 by Osmólska & Maryañska, and consists of a single species, the 3 meters (10 ft) long herbivore Homalocephale calathocercos.

Sporting a flat, wedge-shaped skull roof, H. calathocercos was different from other pachycephalosaurs. Nonetheless, the surface of the skull was greatly thickened, and it had been proposed that males competed in head-butting contests, similar to those of modern iguanas. 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 juvenille trait in many pachycephalosaurid species).

Homalocephale lived in what is now Mongolia, 80 million years ago.