Koolasuchus was a large Cretaceous amphibian that lived on the continent of Australia. It was a carnivore whose diet included turtles, clams and crayfish.
Koolasuchus was a member of the Temnospondyli order of amphibians and specifically of the Chigutisauridae family. It lived in the rift valley where southern Australia was starting to split from Antarctica, and perhaps elsewhere. It is notable both because it was one of the largest temnospondyls, and because it survived long after its cousins further north had become extinct.
Competition with phytosaurs during the late Triassic, and later, crocodilians is believed to have contributed to the general decline of the temnospondyl order. At this point in time Australia was within the Antarctic Circle, and had a climate too cold for crocodiles, protecting them from this competition. Koolasuchus could survive in this colder climate because, like modern salamanders, it is thought to have hibernated under the ice in ponds during the winter.