Megafauna are thought to have evolved to such large sizes to cope with inhospitable climates and food scarcity, with fossils found in Australia of prehistoric emus, tree-dwelling crocodiles and carnivorous kangaroos.
This from an article about finding the fossil of a 'Mega-Wombat'...
The fossil of a car sized mega-wombat has been unearthed in northern Australia, scientists said Wednesday -- the most complete skeleton of its kind.
Weighing in at a whopping three tonnes, the herbivorous diprotodon was the largest marsupial to ever roam the earth and lived between two million and 50,000 years ago.
I think the tree climbing crocs are the scariest. Would have taken care of this guy in a second:
Australian man spends 6 days up a tree to escape crocodiles
