Physical appearance and biologyEdit
Crassigyrinus somewhat resembles a giant tadpole, with tiny vestigal limbs, a powerful streamlined body, and a very large, spade-shaped head. The jaw, with a double row of teeth, is extremely wide, like that of a modern snake, allowing it to swallow larger prey items. It has orange-coloured skin, ostensibly not slimy like modern amphibians, with dappled black spots.
Behaviour and traitsEdit
Crassigyrinus is totally aquatic, living in the fragmented freshwater lakes of Carboniferous Scotland. It was an ambush predator, feeding on anything it could overpower. It was very aggressive, and would attack animals far larger than itself.
A Crassigyrinus stalks Nigel Marven in Carboniferous Scotland, in a lake swarming with giant dragonflies. It initially attacks him when he first enters the lake, wounding his ankle and ruining his attempt to catch a dragonfly. It escapes, and he does not see it. After he succesfully captures a dragonfly the next day, it again moves in to attack him: this time, he sees it first, and captures it, holding it out of the water to examine it. With no way of transporting it back to the park, he releases it back into the water.