Biological information
Time period : Late Carboniferous period
Lifestyle : Carnivore
In the series
Appearances : The Bug House

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'.

Crassigyrinus scoticus is a two-meter (6 ft) long prehistoric amphibian from the Carboniferous period of Scotland. Unlike Proterogyrinus from WWM, its legs were short and stubby, so it could not leave the water. Crassigyrinus scoticus 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.


It was extinct by the Pennsylvanian, when the episode takes place.

The Crassigyrinus wasn't an amphibian, it was a primitive tetrapod.

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