Everything Dinosaur team members have been asked to provide some scientific information on the “Styx Demon”, the pachycephalosaur known as Stygimoloch. The profile of this animal was raised recently due to its appearance in the last “Jurassic World – Fallen Kingdom” film to be released and with the introduction of a Stygimoloch model in the Papo “Les Dinosaures” range.

New for 2020 Papo Stygimoloch model.
The new for 2020 Papo Stygimoloch dinosaur model. A replica of a very spiky pachycephalosaur. Fossils used to erect this genus in 1983 are believed by many palaeontologists to represent juveniles of Pachycephalosaurus. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows the Papo Stygimoloch model.

To view the range of Papo dinosaur figures: Papo Prehistoric Animal Models.

Preparing Stygimoloch Information for a Dinosaur Exhibit

A paper presented at the 2007 annual meeting of the Society of Vertebrate Paleontology suggested that the spiky Stygimoloch was not a valid species of dinosaur, but its fossils represented juveniles of the already described and much larger, bone-headed dinosaur Pachycephalosaurus. With the validity of this genus in question, this makes preparing scientific information for a dinosaur exhibit featuring Stygimoloch a bit of a challenge for our dedicated team members.

Reconstruction of a Juvenile Pachycephalosaurus skull.
A reconstruction of the fossil skull of the juvenile Pachycephalosaurus that has theropod-like teeth in the front of the jaws. The discovery of an almost complete skull and jaws of a juvenile Pachycephalosaurus in eastern Montana (2018), gave palaeontologists the opportunity to learn more about the potential diet of this dinosaur. Picture Credit Brian Boyle (Royal Ontario Museum).

Summarising the Story of Stygimoloch

In 1973, scientists from the Unive‎rsity of California Berkeley, whilst exploring Hell Creek Formation exposures in McCone County, Montana, found a single, robust skull fragment with the remains of three distinct, prominent horns projecting out of the back of it.

Although classified as a bone from a pachycephalosaur, no further work on the bone was carried out until palaeontologists Hans-Dieter Sues and Peter Galton published a comprehensive review of North American pachycephalosaur fossils in 1983. They named Stygimoloch (S. spinifer), based on this unusual skull bone and other fragmentary material that had once been thought to represent part of the neck frill from a Triceratops.

A replica skull of Pachycephalosaurus wyomingensis.
Pachycephalosaurus wyomingensis replica skull. Both Dracorex and Stygimoloch are believed by many scientists to represent juveniles of the already described genus Pachycephalosaurus. Picture credit: Everything Dinosaur.

Picture credit: Everyhting Dinosaur

Rising to the Challenge

Our team members are not ones to shy away from a challenge. As well as providing information on Stygimoloch for the exhibition, they also prepared some additional information featuring Pachycephalosaurus wyomingensis so that visitors could learn more about how perceptions regarding Hell Creek Formation pachycephalosaurs have changed.

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