By Louise Molloy
They’re very rare. They’re very fragile. They’re the amazing, fossil bearing rocks found at McGrath’s Flat in central NSW.
These rocks are packed with fossils, and even a single rock can reveal hundreds of insects! The things found inside range from microfossils, such as pollen and roundworms, to a fossilised last meal half-digested in a fish’s stomach. Put on your 15-million-years-ago goggles, and let’s take a look!
Then and now
At that time, the Australian continent was mostly covered in rainforest. It had separated from Antarctica and South America, and was drifting further north. McGrath’s Flat was a billabong surrounded by rainforest.
What’s more, the microfossils reveal signs of how the Australian continent was changing. The rainforest was drying out and turning into the dry scrub, grassland and deserts that cover most of Australia today.
Detectives at work
It’s taken a lot of detective work from a team of Australian and international scientists to really dig into all these fossils. Their work has opened a window on the environmental change that Australia went through 15 million years ago.
One of the team leaders, Associate Professor Michael Frese from the University of Canberra, used an advanced microscope to look at and photograph the fossils. This helped the team identify the different types of fossilised pollen. As well as rainforest trees, there was also pollen from banksias that would have grown in drier conditions on the fringe of the rainforest.
Also through the microscope, the team could spot pigment (colouring) cells in incredibly well-preserved fossils, including a bird’s feather and a fish’s eye and skin!
Depth of detail
How come these fossils are so well-preserved? The team believe it’s because iron-rich groundwater en-tered the billabong and then covered whatever was in the waterhole in iron minerals. Whatever the cause, the amazing detail is leading to amazing discoveries.
“Many of the fossils that we are finding are new to science and include trapdoor spiders, giant cicadas, wasps and a variety of fish,” explains the other team leader, Dr Matthew McCurry from the Australian Museum and the University of NSW.
There you have it – the exceptional McGrath’s Flat is a rare window with a fabulous view!
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