Fifteen-million-year-old relatives of cicadas have been found on a farm in New South Wales, in a discovery that could shed light on Australia's pre-historic ecosystems.
University of NSW palaeontologist Matthew McCurry, a curator at the Australian Museum, has spent about three years researching numerous species at McGraths Flat, near Gulgong, on the Central Tablelands.
It all began when a farmer stumbled across a rock containing a fossilised leaf.
Each time the scientists went back, they found something new, giving them more insight into the past.
Among trapdoor spiders, wasps and a variety of fish, there sat the first known remains of ancient cicadas in Australia.
"It's telling us a lot about what Australia was like about 15 million years ago," Dr McCurry said.
They found three species related to the singing cicadas we hear in trees today — the loudest insects in the world.
But one of them is much larger, with a single wing measuring up to eight centimetres, about the size of a small bird.
"It's larger than any other cicada we've found in modern day Australia," Dr McCurry said.
The wings themselves have been preserved in good condition, a fact Dr McCurry attributes to the nearby volcanoes which pre-date the site.
"The rocks that the volcanoes had left dissolved away to form the right kind of sediment to preserve these fossils," he said.
A snapshot in time
The insects' fragile bodies are often destroyed by nature before they can become fossils.
"Even though Australia's home to such an amazing diversity of cicadas today we haven't had that information about these species," Dr McCurry said.
"It tells us where these species come from, we can make inferences about how long they've been in Australia and how they've evolved."
He said they were found in high densities there because it was a Miocene rainforest, a dense, wet and hot area perfectly suited to cicadas.
"That's really important for palaeontology because we don't have a lot of good fossils from that point in time or that type of ecosystem," he said.
The researchers believe that environment could have played a role in why the insects were so large.
Dr McCurry says the only cicada species bigger than the fossils they found are in South-East Asia.
"Maybe that suggests these rainforest ecosystems allowed for these cicadas to reach a larger size than they do in other environments," he said.
The species, which reminds many of the sound of our rainforests, still thrives in Australia today.
"It's really our only snapshot of what they were like in the past," Dr McCurry said.
