Megalania was a giant lizard, between 4.5 m (15 ft) and 7.9 m (26 ft) (depending on which size estimate you trust) in length, with a weight of between 331 kg (730 lb) and 600 kg (1,300 lb). Its name means "ancient giant roamer", not "ancient giant butcher" as some mistaken descriptions assert. Megalania lived in Australia during the Pleistocene, between about 1.6 million and 40,000 years ago. Megalania was the largest lizard that ever lived, and because of its size, is sometimes referred to as the "Dragon of the Australian Outback." Megalania is also known as the giant goanna, and it was related to the goanna lizards of today, including the largest extant lizard, the Komodo Dragon, though it is more closely related to the Perentie, Australia's largest lizard today.
Megalania had a mouth full of serrated, razor sharp teeth that curves like scimitars. Judging by its size, it probably ate mid-to-large sized animals, especially giant marsupials like Diprotodon, the giant wombat, and large kangaroos. Lizards the size of Megalania would be unlikely to evolve today due to the absence of megafauna on which they could feed. Judging that the lizard went extinct about 40,000 years ago, around when humans arrived on the continent, it seems likely that humans caused its demise by taking away its food sources -- large animals.
Being a monitor lizard, Megalania was probably intelligent for a reptile. All the monitor lizards have a metabolic rate elevated above other lizards, along with several sensory adaptations that help them hunt live prey. Living monitor lizards can stand on their hind legs and survey their environment, a trait that gives them their name. The most intelligent of lizards, other monitors have been shown to be able to count to six (through careful feeding studies with snails at the San Diego Zoo), fool crocodiles using decoys to steal their eggs, cooperate while foraging, and even have distinct personalities.
There are sometimes reports of living Megalania, though these are almost certainly false, because the reports only started coming in after the species was described in scientific journals.
