Stygimolochs are a juvenile species of the Pachycephalosaurus in which the head transforms as they age. This plant-eating dinosaur came from the order Ornithischia and is a part of the superfamily Pachycephalosauria.

Key Facts

Stygimoloch pronunciationSTIH-jih-MOE-lock
What does Stygimoloch mean?Stygimoloch is the Greek word for “horned demon from the river of death”.  The name has two root words, “Stygi” is from the Greek myth of Chiron, “ferryman of the river of Styx” while “Moloch” came from an ancient Hebrew God which suggests the same name.
Dinosaur typePachycephalosauria
On the menuHerbivore
Length3-5 meters
Height1.4 meters
Weight45-78 kg
Life expectancyStygimolochs have lived for a span of three million years.
Legs used to get aroundBipedal
Estimated top speedThe estimated speed of a Stygimoloch is between 20-30 mph.
When they livedStygimoloch are known to live during the late Cretaceous Period known as the Campanian age between  70-65 million years ago.
Where they have been found?This plant-eating dinosaur is found in North American lands specifically Montana.

When & Where

In 1973, scientists from the University of California Berkeley conducted an exploration along the Hell Creek Formation and found a robust skull fragment that has three prominent horns at the back of it. However, it was classified to be from a Pachycephalosaurus and no further investigations occurred not until British paleontologist Peter Galton and German paleontologist Hans-Dieter Sues conducted a comprehensive review of the North American fossils in 1983, that it indeed came from a Stygimoloch and was named based on its appearance. Further study in the skull bone and other fragmentary materials revealed that it used to represent a part of the neck frill from a Triceratops.

Size & Weight

Stygimoloch may sound like a scary dinosaur when in fact it was only about the size of a fully grown human being. They are classified as small to medium-sized creature that has an average height of about 1.4 meters and a length of between 3-5 meters. Since it is a plant-eating creature, it’s known to have an upper body that is lighter with a small head probably weighing about 45-75 kg.  

Mobility & Diet

Several studies revealed that Stygimoloch has small and serrated teeth making them incapable of chewing tough and fibrous plant materials. Based on the facts presented, paleontologists believed that they have a mixed diet of seeds, leaves and fruits. Having a very light upper body and head allows the dinosaur to move quickly and agilely. The spikes in their heads are said to be used either as a defense mechanism against predators and can even be used during breeding periods. 

Interesting Points

  • Stygimoloch is believed to live for a span of 3 million years here on Earth.
  • Stygimoloch can run as fast as an ostrich.
  • They appeared on an arcade video game “DinoRex” as a playable dinosaur.
  • Stygimoloch is translated as “horned demon from the river of death”.
  • The reason for its intimidating name is because of its ornamented skull which recalls the Christian conception of the devil.
  • Their horns aren’t only dedicated to attacking predators but are also used for breeding.