Australia: The Land Where Time Began

A biography of the Australian continent 

Large Reptilian Predators 

While the other continents had very large predators like sabre-toothed cats and bear-dogs, the top predator in Australia was apparently a very large goanna (monitor lizard) Megalania prisca 5-7 metres long and weighing probably about 600 kilos, about 10 times the weight of a Komodo dragon, the largest living goanna. There was also a smaller, 3-metre long, Pleistocene terrestrial crocodilian, Quinkana fortirostrum, which had teeth similar to those of carnivorous dinosaurs such as Tyrannosaurus. The kangaroos and wallabies of the time, giant and otherwise, would almost certainly have been able to outrun the reptilian predators and even the dog-like ones, as none of them seem to have been designed for speed or the endurance required for a long chase as wolves and other dogs are. Though the extremely efficient locomotion of kangaroos, hopping, would probably allow them to outrun even the endurance predators. Large animals such as the reptiles, and the Thylacoleo were probably ambush predators. The kangaroos were probably in greatest danger from their relatives, the carnivorous kangaroos.

Australia seems to have been "different" for a very long time. Even way back during the Age of Dinosaurs, the Mesozoic, the fauna seems to have been out of sync with the rest of the world. During the Cretaceous, which ended about 65 million years ago, when the dinosaurs and many other animals went extinct and when the Australian landmass was just starting to break away from Antarctica, there was at least one dinosaur that had characteristics of its backbone which had disappeared elsewhere in the previous Period, the Jurassic.

The remains of a labyrinthodont, a large amphibian, has been found in Victoria. Labyrinthodonts are thought to have gone extinct in the rest of the world in the Permian or Early Triassic Period, about 100 million years earlier than the Australian specimen. A new species of labyrinthodont, Koolasuchus cleelandi, was discovered in 1989 near San Remo, Victoria, Australia. In Queensland, another labyrinthodont Siderops, is known from the Jurassic. 

Sources & Further reading

1. John A. Long & Peter Schouten, Feathered Dinosaurs, the Origin of Birds, SCIRO Publishing, 2008
2. Penny Van Oosterzee, 1993, The Centre - The Natural history of Australia's Desert Regions, Reed Australia.