Prehistoric Park Wiki
Prehistoric Park Wiki
Biological information
Time period : Late Carboniferous period
Lifestyle : Carnivore
In the series
Brought back : None
Appearances : The Bug House

Crassigyrinus (meaning "thick tadpole") is an extinct genus of carnivorous stem tetrapod from the Early Carboniferous Limestone Coal Group of Scotland and possibly Greer, West Virginia. The type specimen was originally described as Macromerium scoticum and lacked a complete skull. With subsequent discoveries, Crassigyrinus is now known from three skulls, one of which is in articulation with a fairly complete skeleton, and two incomplete lower jaws. Crassigyrinus grew up to 2 meters in length, coupled with tiny limbs and unusually large jaws. Crassigyrinus is taxonomically enigmatic, having confused paleontologists for decades with its apparent fish-like and tetrapod features. It was traditionally placed within the group Labyrinthodontia along with many other early tetrapods. Some paleontologists have even considered it as the most basal crown group tetrapod, while others hesitate to even place it within the Tetrapoda superclass. Crassigyrinus had unusually large jaws, enabling it to eat other animals it could catch and swallow. It had two rows of sharp teeth in its jaws, the second row having a pair of fangs. Crassigyrinus had large eyes, suggesting that it was either nocturnal, or lived in very murky water.

In Prehistoric Park[]

Crassigyrinus scoticus is a two-meter (6 ft) long prehistoric amphibian from the Carboniferous period of Scotland. Unlike Proterogyrinus from Walking With Monsters, its legs were short and stubby, so it could not leave the water. Crassigyrinus was perfectly adapted to life underwater as it had gills and a strong and powerful tail. Its favorite food was fish and other amphibians, but it may have also attacked some of the giant arthropods of its time including the giant dragonfly Meganeura. Crassigyrinus had a pair of large eyes, suggesting that it was either nocturnal, or lived in very murky water.

Nigel caught a Crassigyrinus during Episode 5, however he had no way to transport it, and The Bug House does not have a pond, so he let it go after nicknaming it 'The Swamp Monster'.


  • It would have already been extinct for around six million years by the Pennsylvanian, when the episode takes place.
  • Crassigyrinus wasn't an amphibian, it was a primitive tetrapod.