This is Crassigyrinus. This boy bites off more than he can chew.
— Allen, about Crassigyrinus

Crassigyrinus (name meaning "Thick Tadpole"), also called The Swamp Monster, is a genus of carnivorous stem tetrapod that originated during the Early Carboniferous in what is now Scotland and North America. Measuring around 2 meters long, these giant amphibians are notable for combining bizarre specializations such as tiny forelimbs, with a number of primitive features.

In the episode "Arthropods Swamp", a single female Crassigyrinus was rescued from the Carboniferous of Scotland 300 million years ago. It resides in the water regions of the Bug Dome exhibit of the park.


Era & DiscoveryEdit

Crassigyrinus lived during the middle to the end of the Carboniferous period, living alongside giant insects, primitive reptiles, and even other amphibians. It was one of the top predators of its time.

The first remains of Crassigyrinus were discovered in 1929, these remains consisted of sections of the skull. Skeletal remains of Crassigyrinus have also been discovered in the Scotland area.

Physical AttributesEdit


Crassigyrinus measured around 6 feet (2 m) long and this bizarre tetrapod had small, thin, but noticeable hind limbs and vestigial forelimbs, making it look a bit like an elongated frog (or a giant tadpole, hence its Greek name). This eel-like creature seemed to have spent most if not, all of its time in the water and its double rows of sharp teeth point to an unmistakably carnivorous diet.

Not like the Proterogyrinus, Crassigyrinus's 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. These have given rise to arguments about its taxonomic status. Not only is it taxonomically bizarre, but it must also have been a remarkable and formidable animal when alive. Crassigyrinus had a pair of large eyes, suggesting that it was either nocturnal and lived in very murky water.

Although these creatures were slimy and powerful, they still have these tiny limbs, only for an animal a quarter of their size, so they weren’t very good on the land. And these amphibians lived in the shallows.

Behavior & TraitsEdit

Crassigyrinus was a solitary hunter, only getting together during mating season. To catch fish and other amphibians, these predators burst out much like a modern-day pike. They were ambush predators with lengthy jaws and they could open their jaws really wide, making it the perfect snap trap. They waited in ambush and whenever prey came nearby, they attacked anything that they could dismember – fish, amphibians – with a double row of fearsome teeth in their mouth, similar to a shark.

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 Meganuera.

Trivia Edit

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