Fossil records indicate that this early lizard, Megalania (Megalania prisca or Varanus priscus), was a whopping seven metres in length. They were part of a megafaunal assemblage that inhabited southern Australia during the Pleistocene. The youngest fossil remains date to around 50,000 years ago. The first aboriginal settlers of Australia might have encountered them and been a factor in their extinction. (Photo by Sky TV/The Guardian)