Riversleigh Fossil Site

Cross section of a gulf snapping turtle shell fossil

Cross section of a crocodile's shin

Thunderbird's leg bone

Thunderbird's vertebrae (we think)

We had a Riversleigh day today. We decided to come down and stay here on our way out of Lawn Hill instead of driving 100k return for a day trip, but on the way down realised that the road is really pretty good and it only takes about an hour to look at the fossil site so… we could have easily done it as a day trip. Oh well. I was a bit annoyed that it costs the same to camp here at Miyumba as it does at Lawn Hill, considering that there we had flush toilets, water, cold showers, rubbish and recycling, and here we just have a pit toilet, but I guess it’s just a standard national parks fee. Still. I can see why we are the only people at this camp site – it’s lovely, just not $20 worth.

Enough complaining – getting here early and setting up we drove a little way back up the road to the Riversleigh ‘D’ Fossil site. This section of the Lawn Hill NP has been world heritage listed (along with Narracoorte in SA) because it is such an important site for fossils – apparently it provides evidence of key stages in the evolution of Australia’s mammals – there are fossils of more than 300 kinds of mammals here, including marsupial lions, carnivorous kangaroos, huge pythons, crocodiles and bats. Apparently when these fossils were created (about 25 million years ago) there were nine different types of crocodiles in Australia! Now there are only two of course…. two too many….shouldn’t say that. The section of the fossil site that the public is allowed to see if ‘D’ site, and there are just fossils everywhere you look which is really cool.

When the fossils were created the area around here used to be more tropical and there was a lake, with the same heavily calcified water which grew into tufa on the surface. This would harden a bit, look like solid ground to animals which would stand on it and promptly sink to the bottom, to drown or get eaten by crocodiles, and then form perfect fossils in the limestone. One of the most commonly found fossils at D site is that of the Thunderbird (or Big Bird as it’s called on a lot of the signs), which was a 2.5m emu type of bird, although funnily enough it had more in common with a modern duck than with the emu. Anyway we saw lots of thunderbird fossils, and some crocodile fossils, and loads of other ones we couldn’t identify. Even more interestingly, from a section of the track you could look out on another section of different, ‘marine’ limestone nearby, which was created 530 million years ago, and which has completely different fossils, because of course the mammals in the fossils we were looking at didn’t even exist then, in fact there weren’t any vertebrates around then and it was a sea bed, so the fossils over there are things like nautiluses. Amazing how much a simple rock can tell you….

After about an hour looking at fossils we came back to the trailer for lunch and have just hung around reading and playing games all afternoon, apart from a quick walk down to look at the river which we’ll cross tomorrow morning on our way out – quite fast flowing water! – and the boys’ favourite, journal writing :-)