The Central Tablelands are dominated by grasses and spindly trees. Some of the area's rusted rocks hide traces of the lush rainforests that covered the area 15 million years ago.
The area, McGraths Flat, is not Australia's only Miocene deposit, but these new fossils are a paleontological boon because of their exquisite preservation. Paleontologists have excavated flowers, insects, and even a bird's feather over the past three years.
The site, which was discovered by scientists in the journal Science Advances, opens a whole new area of exploration for Australian paleontology, said Scott Hocknull, a paleontologist at theQueensland Museum who was not involved in the research.
An oxbow lake, known as a billabong in Australia, was created 15 million years ago when a river carved through the jungle. The stagnant pool kept scavengers at bay, allowing plant material and animal carcasses to accumulate. The iron in the billabong came from nearby basalt mountains, which caused the pool's low pH to cause the iron to form. Goethite is a dense, iron-rich rock and is where the fossils at McGraths Flat are preserved.
This method of fossilization is rare. Paleontologists often overlook quality fossils because they are rare in igneous rocks. Goethite, which is common in Australia, can yield remarkable fossils.
There is no shortage of goethite. We are essentially a rusting country.
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Matthew McCurry is the curator of paleontology at The Australian Museum.
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Michael Frese has a description of a flower.
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A wasp.
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Michael Frese is a researcher at the University of Canberra.
Many of the fossils from McGraths Flat have a metallic sheen because of their iron-tinted origins. The goethite is crawling with fossils. The researchers have found a collection of insects in the stone as they split it apart. Some ancient flies have their compound eyes preserved.
More than a dozen archaic arachnids have been found at the site. Michael Frese, a co-author of the study and a researcher at the University of Canberra, compares spiders to squishy bags of liquid. Australia's fossil record of spiders was almost completely absent before the start of the McGraths Flat.
Matthew McCurry, the curator of paleontology at The Australian Museum and the study's lead author, said that the fossils are so well preserved that the paleontologists were able to observe relationships between species. The team observed parasites fastened to a fish's tail.
The rainforest's inhabitants were examined using an electron microscope and microphotography techniques. Dr. Frese found a clump of pollen on the insect's head.
Dr. Frese said that they could tell which flower was visited by the sawfly before it fell into the water. If the quality of preservation was not high, that wouldn't be possible.
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An ancient feather.
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An ancient spider, which Dr. Frese likens to squishy bags of liquid.
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A sawfly is in the rock.
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The Australian Museum has a fossil fish.
The rainforest was surrounded by drier environments and it's likely that the remnant patch of a once larger forest is McGraths Flat. Considering the trends of the Miocene, this makes sense.
Australia was drifting northward when the insects scurried around the billabong. The climate dried out as it traveled, leading to the extinction of many species.
The researchers believe that the dramatic climate transition affected particular species within the rainforest. Some insects found at McGraths Flat are now found in northern Australia, while others are only found in remnant pockets of rainforest.
The species that were better able to adapt to those changes were studied. Predicting which are most at risk in the future is something we can do.
Dr. Frese said that the breadth of species preserved in McGraths Flat made it particularly useful for reconstructing ancient ecosystems.
The site is different because it is all small fossils, but I think it will tell us more about what has happened in the environment. You don't need to find a one-ton terror bird to tell this story.
