Foraminacephale (meaning "foramina head") is a genus of pachycephalosaurid dinosaur from Late Cretaceous (Campanian stage) deposits of Canada. Description Foraminacephale, as a pachycephalosaurid, was a small, bipedal herbivore with a thickened dome on its skull. In 2016, Gregory S. Paul estimated its length at , its weight at . In Foraminacephale, the top surface of the dome is punctuated by many small pits, the eponymous foramina; the dome itself consists of a large, central lobe with a sloped frontal half, and two smaller lateral lobes at the front. The squamosal bone forms a tall bar of completely smooth bone underneath the dome, save for six bony nodes that line the bottom edge of the dome and an additional "corner" node just below. These features differentiate Foraminacephale from all other pachycephalosaurids. Unlike Stegoceras, Hanssuesia, and Colepiocephale, the parietal bone of Foraminacephale (which constitutes the back part of the dome) projects backwards and downwards over the base of the skull. Two traits also differentiate Foraminacephale from Sphaerotholus and Prenocephale: there are prominent grooves between the central lobe and the lateral lobes, and the opening of the temporal bone is slit-like. Ontogeny As with Stegoceras, the wide age range present in specimens of Foraminacephale allows for analysis of the ontogeny, or growth, of the dome. Measurements of 27 different points on 21 Foraminacephale skulls showed that the dome became proportionally taller with age, but did not become significantly wider. Histology of the specimens showed that the domes became less porous with age - the smallest specimen's skull was 1.67% empty space, while the largest specimen's skull was 0.25% empty space. Generally, the frontal part of the dome was more porous than the parietal part. The growth series of the dome allows Foraminacephale to be differentiated further from Stegoceras. In young Stegoceras, the dome is flat; however, in even the smallest Foraminacephale specimens, the parietal is already slightly domed. The supratemporal fenestrae on the top of the skulls of Foraminacephale are slit-like, as opposed to Stegoceras where they are round, and they seal shut very early in ontogeny as opposed to remaining open more-or-less throughout the animal's lifespan. The amount of empty space in the skull roof was also smaller relative to Stegoceras, and more similar to Acrotholus. Furthermore, in Foraminacephale, the squamosal and postorbital bones became part of the dome much quicker, the dome thickened at a slower rate, and the sides of