Prenocephale (meaning "sloping head") was a small pachycephalosaurid dinosaur genus from the Late Cretaceous (Maastrichtian) of Mongolia and was similar in many ways to its close relative, Homalocephale, which may simply represent Prenocephale juveniles.
Description[]
Prenocephale
Adult Prenocephale probably weighed around 130 kilograms (290 lb) and measured around 2.4 metres (8 ft) long. Unlike the flattened wedge-shaped skull of Homalocephale (a possible juvenile trait also potentially seen in early growth stages of Pachycephalosaurus), 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 the Nemegt Formation, 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 tall hind legs.
The head of Prenocephale was comparable to that of Stegoceras, albeit with closed supratemporal fenestrae. Also, the paired grooves above the supraorbitals/prefrontals (along with a posterior parietal that restricts the frontal dome) are absent in Prenocephale. This differentiates the species from Stegoceras, as such features are common in the latter. The North American Sphaerotholus was considered a synonym of Prenocephale by Sullivan (2003), but Longrich et al. (2010) and Schott and Evans (2016) 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.
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Paleobiology[]
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