Saturday, 27 November 2010

It's not so hard to believe in Megalania

Occasionally, when a species colonises an island, it undergoes ‘insular gigantism’ and grow to several times their initial size. Until recently, this theory was used to account for the large size of the Komodo dragon (pictured above).

But it turns out dragons are not an oddity of island evolution – they’re one of the few surviving relics from an era when large-bodied carnivores roamed Australia and Southeast Asia. Three sites have been discovered across Queensland that contain fossils of dragons the same size as the creatures we see today, says Scott Hocknull, the senior curator of geosciences at the Queensland Museum. 

“Our data reject the long-held perception that V. komodoensis became a giant because of insular evolution,” Hocknull and colleagues wrote in the journal PLoS One in 2009. “The Komodo dragon first evolved on mainland Australia, probably in response to the Megafauna,” he says. The Australian fossils range from 3.5 million to 300,000 years old, though dragons might have been around until the Megafauna extinction 50,000 years ago.

About 3.5 millions years ago, dragons were the dominant lizard in Australia. Then, 1.8 million years ago, an even more fearsome lizard emerged; Megalania (Varanus prisca) could grow up to 5.5 m long and weigh 600 kg. 

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