Prenocephale

*Prenocephale prenes*

* Jurassic Park Institute Artwork
* Robert F Walters Artwork

***Prenocephale*** was a dubious species of small pachycephalosaurid dinosaur from the Late Cretaceous of Mongolia and was noticably similar in many ways to its close relative, Homalocephale, which may specuated to possibly represent Prenocephale juveniles. Prenocephale had an 8-inch thick skull, and had large eye sockets. However, there are no clues to what its body looked like.

## Description

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.

## 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* (and the other pachycephalosaurs) browsed on leaves and fruit.

## JPInstitute.com Description

Prenocephale was a bone-headed member of the same family that included the better-known Pachycephalosaurus. It isn't known exactly what these dinosaurs ate, but some scientists think that, just like humans, they may have been omnivorous - eating both meat and plants.

Prenocephale was a two-legged creature with five fingers on each of its hands, rare for a Late Cretaceous dinosaur. Its eyes were located on the side of its head, but it appears as though they had the ability to face somewhat forward. When this feature is coupled with its large optic nerve, it is possible that this animal could have had (or been in the process of evolving) stereoscopic vision, a tool useful for a predator. This type of eye arrangement is found to lesser degrees in other pachycephalosaurs.

## Links

http://web.archive.org/web/20040806052719fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_preno.html#