Adult Prenocephale probably weighed around and measured around long. Unlike the flattened wedge-shaped skull of Homalocephale, the head of Prenocephale was rounded and sloping. The dome had a row of small bony spikes and bumps. It lived in what is now Mongolia, but in high upland forests, not the dry deserts of Mongolia today. Like some other pachycephalosaurs, Prenocephale is known only from skulls and a few other small bones. For this reason, reconstructions usually depict Prenocephale as sharing the basic body plan common to all of the other Pachycephalosauria: a stout body with a short, thick neck, short forelimbs and tallhind legs. The head of Prenocephale was comparable to that of Stegoceras, albeit with closedsupratemporal fenestrae. Also, the paired grooves above the supraorbitals/prefrontals are absent in Prenocephale. This differentiates the species from Stegoceras, as such features are common in the latter. The North AmericanSphaerotholus was considered a synonym of Prenocephale by Sullivan, but Longrich et al. and Schott and Evans kept it as a distinct genus based on cladistic analysis. Homalocephale has been viewed as a possible juvenile of Prenocephale due to the lack of a dome and its discovery in the same location and chronological interval, but new specimens of Prenocephale, including a juvenile specimen, suggest that Homalocephale, even if its holotype is a juvenile, is distinct.
Classification
Prenocephale is a member of the Pachycephalosauria, a large clade of herbivorous/omnivorous dinosaurs from the Late Cretaceous. Robert Sullivan considered Foraminacephale, "Prenocephale" edmontonensis, and Sphaerotholus goodwini to form a clade with the Asian taxon P. prenes. He considered Tylocephale the sister taxon to the Prenocephale clade, while sinking Sphaerotholus buchholtzae as a subjective junior synonym of "P." edmontonensis. They all possess a distinct row of nodes on the squamosal and parietal areas of the skull roof. Below is a cladogram modified from Evans et al., 2013.
Paleobiology
As with most of its relatives, scientists do not yet know what these dinosaurs ate. However the premaxillary teeth and muzzle are not as wideset as in its relative Stegoceras, indicating different feeding preferences, possibly that Prenocephale was a more selective forager. Some scientists suggest that it may have been an omnivore, eating both plants and insects. However, most experts agree that Prenocephale browsed on leaves and fruit.
