Was Australia ever short on deadly animals? About 1.5 million years ago [MYA] until merely 40 thousand years ago a giant monitor lizard stalked the wilderness (art by Vlad Konstantinov). Varanus priscus, also known as Megalania prisca, became 5.5 to 7 m (18 to 23 ft) long and a weight of ca 600 kg (1,320 lb), making it the largets lizard ever and an apex predator that humans likely faced.