3 days ago
Palaeontologists verify Australia's largest fossil pearl as 100 million years old
An "incredibly valuable" fossil pearl, slightly bigger than a marble, has been uncovered in outback Queensland.
The precious find was dug up in Richmond — between Mount Isa and Townsville — an area renowned for its significant fossil discoveries.
University of Queensland palaeontologist Gregory Webb, who verified the fossil pearl over two years, said it was the largest of its age found in Australia.
At nearly 2 centimetres in diameter, he said it was "bigger than a typical marble".
"From a scientific point of view, it's incredibly valuable and extremely rare."
The fossil pearl was found by a tourist visiting Richmond's Kronosaurus Korner museum in 2019.
Tourists in the town of about 500 people can obtain a permit to dig in the museum's palaeontological pits under the provision they donate anything they find of scientific value.
Long-time volunteer digger Barbara Flewelling accepted the intriguing artefact from the tourist.
"We've been volunteering at Kronosaurus Korner for 17 years and this is the first one that we're aware of."
She said staff turnover at the museum and pandemic lockdowns delayed its verification in Brisbane.
The precious find was then assessed by Professor Webb and a small team of researchers for nearly two years.
"We have undertaken some really high-tech analysis of this particular specimen so that we could look inside it without damaging it, and we have verified it is in fact the pearl," he said.
Professor Webb said under other circumstances it likely would have been a faster process.
"There aren't very many palaeontologists and the technology is in huge demand," he said.
The pearl has been returned to Richmond, where it is now on display at the museum.
Professor Webb said only two other prehistoric pearls, both dug out of Cooper Pedy in South Australia, had been verified in Australia.
But he said those finds were smaller and technically opalised pearls, not the original pearls.
He said the "incredibly high quality, real scientific treasure" found at Richmond had barely been altered in its 100 million years.
Professor Webb said that was due to the pearl forming in a clamshell composed of the mineral calcite, which was more stable than aragonite, the material that modern-day pearls were largely composed of.
While the pearl is rare, the Inoceramus bivalve clam that made it was common during the Cretaceous period 100 million years ago.
The extinct giant clams grew up to 50cm in diameter in what is now outback Australia, but could reach up to 2 metres in other parts of the world.
Richmond, where the fossil pearl was found, was 40m underwater covered by the inland Eromanga Sea, which stretched from Cape York to northern New South Wales.
The area, known for its fossils, draws visitors from across the globe, who have unearthed other underwater creatures such as the Kronosaurus and Ichthyosaurus.
Kronosaurus Korner founder Rob Ivers said findings such as the pearl would help tourism in the region.
"Obviously, people from across the country hear something like this travelling through Richmond, they'll certainly call into the museum," he said.
Professor Webb said discoveries such as the pearl helped scientists understand how fauna adapted to changes in climate.
"Ancient clams were similar to modern clams in that if they got some irritant inside the shell, they would simply grow shell around it to protect themselves," he said.
"By looking at how ancient biology, ecosystems and individual communities adapted to things that were changing around them, it gives us a better understanding of how our modern biology reacts as well.
"That helps us project what might happen in the future."
