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SAM & Cave Divers AA explore sinkhole megafauna

Jacinta Bowler, Researchers dive deep for megafauna in South Australia sinkholes, Cosmos, 4 November 2023

Mt Gambier in regional South Australia is well known for its incredible sinkholes, but below the fish and yabbies sits ancient creatures waiting to be discovered.

At the Cave Diving Association of Australia’s (CDAA’s) 50th Anniversary meeting, researchers and other members are diving deep into these sink holes to discover fossils of extinct marsupial megafauna.

“Palaeontology is more than just studying dinosaur bones,” said Griffith University Associate Professor Julian Louys.

“Where the fossils come from, their context, age, and relationship to other fossils is critical information we use to understand past environments and how climate change impacted ecosystems in the past.”

The dives at the Englebrechts, Gouldens and Tank caves are part of a collaboration between the CDAA, Griffith, the University of Queensland, University of Adelaide and the South Australian Museum.

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From top, Damian Bishop from CDAA, A/Prof Julien Louys from Griffith University, and Steve Trewavas and Joe Monks from the CDAA. Credit: Carley Rosengreen/Griffith University.

Although many members of the CDAA are not traditional scientists, Louys told Cosmos that their work is critical.

“We couldn’t do any of the work that we do without them,” said Louys.

“It’s a genuine sharing of knowledge. I teach them what to look for, what we’re doing and the sorts of samples that we might be collecting. In return they teach me how to dive in these caves and provide access to places that I wouldn’t otherwise be able to get to.”

The team has found plenty of fossils of megafauna – including a skull of what could be a short-faced kangaroo. But they’re also looking to try and get a fuller picture of the life of these animals. Everything from pollen samples to ancient DNA could be preserved in the watery depths.

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The skull of a large kangaroo was retrieved from the depths of Gouldens sinkhole. Credit: Carley Rosengreen/Griffith University.

“What is really special about [these cave systems] is that they are in these underwater settings,” Louys told Cosmos.

“Because they’re in these underwater settings, they haven’t been disturbed for 10,000s to 100,000s of years.”

The team has also deployed a dosimeter – which tracks radiation – to give more accurate date ranges for the bones they’re discovering.

While the researchers and cave divers have now finished their exciting dives, there’s plenty more to be done.

“Now it’s about going through and making sure that the bags are correctly labelled, and every sample is properly accounted for,” Louys concluded.

“It’s not just a matter of diving in there grabbing a bone and then coming out again, we’re doing this in a systematic and scientific way as possible, which means a lot of documentation.”