Ancient Australian Crocodiles

Chris - Tell us about this new piece of information that tells us about crocodiles in Australia.

Paul - This is a fascinating find up in Gladstone in Queensland: that's more or less where the Tropic of Capricorn intersects the coast. They've got a couple of skulls of an early member of a group of crocodiles called the mikosuchines, which is a subfamily of crocodiles. This particular group of crocodiles are only found in Australia and the South West Pacific. The earliest members of the group are typical crocodiles with a flat broad snout. Later on in their evolution, about 25 million years ago, this particular group of crocodiles took on all of types of different shapes and sizes. There were hatchet-heads with huge fangs; terrestrial crocs that hunted on land; and even tiny ones that we think climbed trees and filled the goanna niche. All these belong to this one sub family. Finding an early member of these crocodiles is a really important find.

Chris - Am I right in thinking that crocodiles predate dinosaurs to a certain extent?

Paul - Actually they more or less got going at the same time as dinosaurs. The earliest crocodiles in the world occur at about 220-230 million years old. This is about the same time that the first dinosaurs were romping around in South America. If you saw an early crocodile walking down the street, you wouldn't recognise it as one of the ones Steve Erwin works with.

Chris - If they were around at the same time, why is it that whatever wiped out dinosaurs didn't wipe out crocodiles?

Paul - The crocodiles that actually made it through the K/T boundary were actually quite small: less than about 25 kilograms. When you're that small, there are lots of places in the environment in which you can hide. Crocodiles also have the ability to go into torpor, or slow down, which maybe the dinosaurs didn't have. So there are a few reasons why, although we'll never know for certain.

Chris - What about your book 'Digging Up Deep Time'?

Paul - I've spent a good part of my life working as a palaeontologist and did a PhD on ancient crocodiles. I then realised that people don't want to employ you just because you know a lot about dead crocodiles, and so I ended up in the media! 'Digging Up Deep Time' is about what its like to be a palaeontologist and how it is to be going around a digging up fossils in Australia. It also a story of the history of life through the eyes of Australian fossils. We even have the oldest turd in Australia! This was found on Kangaroo Island. The book is out in mid - March. The best way to get it is to go to the ABC shop online.