Megalania refers to an extinct giant goanna or monitor lizard, recognised as either Megalania prisca or Varanus priscus. They were part of the megafaunal assemblage that inhabited southern Australia during the Pleistocene. The youngest fossil remains dated to around 50,000 years ago. The first aboriginal settlers of Australia might have encountered them and been a factor in their extinction

No complete skeletons or intact skulls of Megalania are known, and the limited amount of skull material found to date was not associated with postcranial material. Vertebrae and isolated teeth are the most common fossils, and lower jaws and limb bones have also been found.

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https://australianmuseum.net.au/learn/australia-over-time/extinct-animals/megalania-prisca/