The Labyrinthodont (later identified as Rhinesuchus in The Complete Guide To Prehistoric Life) was a prehistoric amphibian from what is now South Africa. It lived during the Permian. Its name means "Crocodile Nose".
Being a giant amphibian that lays in ambush underwater as a crocodile does, labyrinthodonts depended heavily on water as other amphibians do and could live with several others of their kind. Before their water environment dried up, these giant amphibians burrowed into the damp mud and formed a cocoon around themselves in a last ditch attempt to sit out the drought, but if they were found in their torpid state by predators, they'd be helpless.
A Labyrinthodont appeared in the third episode. It was living in a local waterhole. It was first seen attacking a Gorgonopsid by accident. It then escaped and swam away. After a herd of Scutosaurus drank most of the water in the waterhole, the Labyrinthodont was seen resting on shallow water. It then swam into deep water when a Gorgonopsid arrived. When the dry season hit, all of the water evaporated therefore leaving the Labyrinthodont stranded. It wrapped itself in a cocoon just before a Gorgonopsid unearthed the animal and ate it.