Though Australia is typically regarded as a dry and hot country, millions of years ago it was covered in rainforests. The McGraths Flat fossil site provides answers into the landscape of ancient Australia and additional information on how changes in climate impact ecosystems.
Every fossil provides a glimpse into a past world with plants and animals that are often very different to those that we can see on today.
However, most fossils preserve only hard body parts like shells, bones, and teeth, which leaves palaeontologists with many questions about how organisms without hard parts looked like.
Equally challenging is the reconstruction of soft tissues, even if bones or other hard parts have survived.
A handful of fossil sites around the world preserve soft tissues of organisms, as such these sites are extremely important for studying how life has changed over time.
Given the term, “Konservat-Lagerstätten”, defined as fossil deposits that are known for exceptional preservation of fossilised organism, a team from the Australian Museum published an article in the international journal, Science Advances, of a site found in Australia.
Matthew McCurry, scientific officer and curator of palaeontology at the Australian Museum, was a primary author on ‘A Lagerstätte from Australia provides insight into the nature of Miocene mesic ecosystems’.
The Konservat-Lagerstätte site, located in central New South Wales, was named McGraths Flat, after Nigel McGrath who discovered the first fossils at the locality.
McGraths Flat provides unprecedented insight into the time of the Miocene, approximately 15 million years ago, when rainforests covered most of Australia.
The site contains a range of fragile and soft-bodied organisms that are normally missing from the fossil record, like insects or spiders.
Normally, soft bodied organisms tend to decompose before they are covered by sediments and the process of fossilisation, which preserves their appearance, begins.
This is increasingly relevant, as up until a few years ago when work began at McGraths Flat, only four fossil spiders had been found in the whole of Australia. At McGraths Flat, researchers have so far unearthed thirteen spiders, which often are completely preserved.
A multitude of insect groups are also preserved in high levels of detail, which includes dragonfly nymphs, assassin bugs, cicadas and parasitoid wasps. Almost all of them represent species that are new to science and have not yet been named.
The site holds additional significance, because of how it holds information about how the changes in the climate impacted ecosystems.
Through using pollen and spore grains preserved in the sediments at this fossil site, researchers were able to date the fossils to the Miocene epoch, a time where Australia changed dramatically.
Widespread rainforests were replaced by the deserts and shrublands that now dominate the landscape and present in the fossils, is some evidence that the ecosystem was in a state of change.
The pollen suggests that there might have been dryer habitats surrounding the rainforest, which indicates that rainforests in NSW might have already begun changing into dryer habitats at the time.
Over the coming years, researchers have plans to continue excavating the site to learn more about the Miocene environment and to use the gathered information to better predict how modern Australian environments may respond to climate change.
References:
McCurry, M.R., Cantrill, D.J., Smith, P.M., Beattie, R., Dettmann, M., Baranov, V., Magee, C., Nguyen, J.M.T., Forster, M.A., Hinde, J., Pogson, R., Wang, H., Marjo, C.E., Vasconcelos, P. and Frese, M. 2022. A Lagerstätte from Australia provides insight into the nature of Miocene mesic ecosystems. Science Advances, 8(1).
