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"Heya, buddy. You thinking what I'm thinking?"
Owen Grady talking to Stiggy.(src)

Stygimoloch ("demon from the river Styx") is a dubious genus of the pachycephalosaur family living in the Late Cretaceous period. It was distinguished from other pachycephalosaurs by the row of spikes on the back of its head, behind the dome characteristic of the family. Jack Horner has presented evidence in 2009 (and others after him) that suggests that Stygimoloch might be the juvenile form of Pachycephalosaurus.


The Stygimoloch is smaller than the Pachycephalosaurus, but is more robust with a very thick neck. The head is really big compared to the body size, the spikes are slightly different in arrangement, has a goat-like pupil which is unlikely, the torso is too short, has a much larger dome on its head, the tail is too flexible, and has pronated wrists with claws on all five digits. The coloring is mostly reddish, with an creamy underbelly, some black lightning marks on its back and head, a white dome, dark grey spikes, a dark grey streak around its dome, dark grey and dark brown patterning all over the body.


Like their cousin Pachycephalosaurus, the Stygimoloch are shown to be defensive and very strong. When provoked by something like a whistle or a scream, they will charge at the one who provokes it. This is seen with Owen Grady as he whistle an individual named Stiggy to break the prison door for him and Claire. This individual is also provoked by a woman who screamed at the appearance of the dinosaur, resulting in a rampage. The dinosaur is strong enough to break a wall, but not steel. Despite this, the Stygimoloch can be playful to each other too. This is seen after Ben released two of them in King Dino's Prehistoric Playland before he is confronted by the owner.



Stygimoloch was created by InGen for their new park called Jurassic World. As it was not featured in any official Jurassic World material, the exact attraction in which it was included is not known. It could be that it was at the Pachy Arena attraction, alongside its taxonomic cousin Pachycephalosaurus. According to the DPG, Stygimoloch was subject to cruelty some time in the past.[1]

Jurassic World: Fallen Kingdom

It is revealed that there were surviving Stygimoloch populations on Isla Nublar, although they faced the impending danger, alongside many other creatures, in the form of an erupting volcano. Two Stygimoloch were with Owen when they were running from the volcano eruption alongside other dinosaurs.

At least five Stygimoloch were rescued from Isla Nublar, including an individual named Stiggy, who was maneuvered by Owen Grady into freeing himself and Claire Dearing from their cells in Lockwood Manor. Stiggy's escape disrupted the auction, thus preventing the sale of any more dinosaurs before he fled into the wilderness. The other Stygimoloch were eventually freed by Claire and Maisie Lockwood and escape the Manor alongside all of the other dinosaurs.

Jurassic World: Chaos Theory

Season 1

"Halfway Home"

At King Dino's Prehistoric Playland, Sammy Gutierrez and Ben Pincus find a sign advertising real Stiggies. Ben admits that anything's possible nowadays, but they could also be Komodo dragons in bald caps. Bobby Nublar proves to have three Stygimolochs as public show dinosaurs whom he badly mistreats, much to Sammy and Ben's disgust. Unwilling to let the dinosaurs be abused, Sammy and Ben break them out and they wreak havoc on the place before escaping.

Jurassic World: Dominion

By 2022, the Department of Prehistoric Wildlife had reports of Stygimoloch individuals at Seoraksan National Park in South Korea and another being hunted by lions in Nairobi, Kenya, and had apprehended two individuals, one found being illegally transported near San Jose in Costa Rica and a sick one transported by a farmer to a paleo-sanctuary in Queensland, Australia.[2] At least one Stygimoloch was captured and held within the Malta Black market, possibly escaping in the wild again after the collapse of Biosyn. Several Stygimoloch were captured by Biosyn and transported to its sanctuary where they were part of the dinosaurs taking refuge in the headquarters after its president caused a forest fire. It is likely that these individuals also resides in the wild or continue to stay in the sanctuary which is now global.


Promotional Images

Jurassic World: Fallen Kingdom

Jurassic World: Chaos Theory


Jurassic World: Dominion



  • The inclusion of Stygimoloch in Jurassic World: Fallen Kingdom was directly challenged by Jack Horner, as he had proposed the initial theory that it was a juvenile Pachycephalosaurus. Despite this, Stygimoloch was kept in.[3]
  • According to sound designer Al Nelson, the dinosaur's sounds were recorded from a dachshund mixed with camel and pig sounds.[4]

Notes and references