Mating flies found in huge cache of Australian amber

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Mating flies found in huge cache of Australian amber

By Liam Mannix

Scientists have unearthed a huge cache of fossilised Australian amber filled with flies, baby spiders, midges and plants from between 40 and 230 million years ago.

The work sheds new light on what Australia looked like when it was part of the supercontinent Gondwana, which also included South America, Africa, India and Antarctica.

Until now Australia’s amber record from that time was essentially empty.

A rare example of ‘frozen behaviour’ in the fossil record of two mating, long-legged flies in clear, honey-coloured amber from Anglesea, Victoria, dated to about 41 million years ago.

A rare example of ‘frozen behaviour’ in the fossil record of two mating, long-legged flies in clear, honey-coloured amber from Anglesea, Victoria, dated to about 41 million years ago.Credit: Jeffrey Stilwell / Supplied

More than 5800 chunks of amber taken from nine sites, including an oil well in the middle of Bass Strait and the Anglesea coal seams west of Melbourne, contain the first Australian fossils of ancient Gondwanan ants and slender springtails, tiny wingless creatures never before seen here.

The amber not only preserves animals and insects, but freezes them in a still-life scene. One chunk even captures a pair of long-legged flies in what appears to be a mating act.

That’s why “amber is considered to be a Holy Grail in the discipline,” said Associate Professor Jeffrey Stilwell, a palaeontologist at Monash University who led the project.

A large piece of amber with two flies and the first ever Australian fossil of a large mite of the extant genus, taken from Anglesea, Victoria. This chunk is about 41 million years old.

A large piece of amber with two flies and the first ever Australian fossil of a large mite of the extant genus, taken from Anglesea, Victoria. This chunk is about 41 million years old.Credit: Enrique Peñalver

The six-year project released its first findings on Friday. But for the scientists, this is really the start of the journey. Once home isolation is over and they can return to the lab, they plan to start analysing just what’s in the treasure trove of amber they have collected.

Amber is made when tree resin – not sap – drips down a trunk. Resin is a tree’s defence mechanism, designed to stick to any insects that might try to eat it.

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If the resin falls in the right place, like a swamp or forest, it can harden and be preserved. Over time those forests turn into fossil fuels like coal.

With the help of about 30 volunteers, the project team has spent the past few years smashing coal to bits with hammers and picking out the amber preserved inside.

A flake of clear yellow amber from Anglesea, Victoria, containing a new, beautifully preserved biting midge. This flake was dated to about 41 million years old.

A flake of clear yellow amber from Anglesea, Victoria, containing a new, beautifully preserved biting midge. This flake was dated to about 41 million years old. Credit: Monash University / Supplied

What did they find inside?

“Unfortunately, it seems Australia has been host to biting midges for a very long time,” says Dr Andrew Langendam, one of the team’s microscopists.

They also found new species of flies, mosses, ants, and “mites which have these big long legs on them,” Dr Langendam says. “And we found hexapods – tiny little bugs less than a millimetre long called springtails.”

The amber comes from different times in Australia’s history. Put together, they give us a window into the enormous changes the continent has undergone.

The most ancient amber, found in Tasmania, is about 230 million years old. That would have formed when Australia was part of Pangaea, the supercontinent that made up of all the Earth’s land.

About 200 million years ago it broke in half, and Australia’s section – known as Gondwana – headed south. During this time, known as the Jurassic, the Earth was warmer than it is today, there was no Antarctic ice-sheet, and Gondwana was covered in thick rainforest populated by dinosaurs.

Some of the insects caught in amber likely came into contact with those dinosaurs, and maybe even sipped their blood. Sadly, there is no chance of finding dinosaur DNA inside, Jurassic-Park style.

“DNA does not get preserved for that long. Amber is not airtight. DNA will degrade,” says Dr Langendam.

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