A Review of the Pachycephalosaurus Model from CollectA

The pachycephalosaurs, often referred to as the “bone-headed dinosaurs” due to their greatly thickened skulls are a group of ornithischian dinosaurs known almost exclusively from Upper Cretaceous deposits of North America and northern Asia.  Although the majority of this group are only known from fragmentary fossil remains, most notably frontal and parietal bones of the skull,  a number of pachycephalosaur models have been made and this is a review of the Pachycephalosaurus dinosaur model manufactured by CollectA.

Pachycephalosaurus Dinosaur Model

No complete skeleton of Pachycephalosaurus has been found, so interpretations of this dinosaur, the largest of the “bone-headed dinosaurs” discovered to date, are usually based on a scaled up version of the pachycephalosaur known as Stegoceras.  CollectA have depicted their Pachycephalosaurus in a bipedal pose with strong hind legs, five fingered hands and with a tail a fraction longer than the length of the shoulder girdle to the pelvis, although the actual body proportions are unknown.

The CollectA 2013 Pachycephalosaurus Dinosaur Model

A lithe Pachycephalosaurus dinosaur model.

Skull Fossil Fragments

Skull fossil fragments ascribed to Pachycephalosaurus are known from Canada and the western United States, mainly from the Province of Alberta and the states of Wyoming and Montana. The thickened skull dome is over 25 cm thick on larger specimens, exceptional protection for what was a relatively small brain inside the skull.   The model makers at CollectA have elected to give their Pachycephalosaurus a more rounded skull, rather than the very domed shape seen in some reconstructions.

The skull dome was edged with a number of bony protrusions and spikes, these were most prominent towards the back of the skull.  The muzzle was relatively short and it ended in short beak,  in the CollectA replica, the beak is ever so slightly pointed and can be clearly made out on the model.  The spikes and bony projections have been painted a bright yellow colour which contrasts nicely with the muted, camouflaged tones of the body.

 The CollectA Pachycephalosaurus Viewed Close Up

A close up of the lovely detail on the head.

Picture credit: Everything Dinosaur

Model Measurements

The model measures a little over ten centimetres long, although the size of this dinosaur is not certain from the fossil evidence, based on a 4.6-metre-long adult animal we estimate that this Pachycephalosaurus is in approximately 1:46 scale.

The replica has a row of prominent, triangular spikes running from the base of the skull to the almost the very tip of the tail, a single line of spikes is also depicted on the neck, presumably providing some protection from attack and to protect the soft tissue of the neck when browsing on thorny plant material.

The neck looks quite long and stiff. The total number of vertebrae is unknown for any member of the pachycephalosaur family, indeed how the neck bones articulated with the skull of Pachycephalosaurus is open to speculation.  It had been thought that the thickened skulls and stiffened dorsal vertebrae of this type of dinosaur were adaptations for head-butting contests between individuals, although recent studies and biomechanical analysis of the skull domes have led to this form of intra-specific conflict being disputed.

To read more about the disputed theory regarding head-butting Pachycephalosaurs:

Evidence for head-butting dinosaurs: Head-Butting Dinosaurs After All.

Contrasting evidence, pachycephalosaurs may have used their reinforced skulls in different ways: Bone-headed Dinosaurs “bashed” in Different Ways.

This model is supplied on a base, this prevents the feet from having to be oversized and the effect is to depict Pachycephalosaurus as an agile, strong-running dinosaur.  The number of fragments of skull bone found in locations such as the Dinosaur Provincial Park Formation of Alberta suggest that pachycephalosaurs were the most common, small-bodied dinosaurian herbivores in those ecosystems where their fossils have been found.

This is a fascinating re-creation of Pachycephalosaurus and an excellent addition to the CollectA range of prehistoric animal models.  The Pachycephalosaurus replica and the rest of the CollectA prehistoric life range is available from Everything Dinosaur, the UK based retailer of dinosaur models, toys and games that is staffed by parents, teachers and real dinosaur experts.

To view Everything Dinosaur’s range of CollectA models: CollectA Prehistoric World/Prehistoric Life.