Wednesday, December 2, 2020
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The opal fossils that changed a miner’s life and introduced a new species from Australia’s deep past

The opal fossils that changed a miner's life and introduced a new species from Australia's deep past
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Looking inside the bag of precious opals, Mike Poben knew he’d found something special, he just wasn’t quite sure what.

As an opal dealer, he’d seen plenty of gems over the years — Mike found his first when prospecting around Coober Pedy at 16.

He licked the dirt off a dull rock, and when the sun hit its sides, it filled with gem colour and revealed an opalised mussel shell.

He was hooked.

In the decades following that first discovery, Mike dipped in and out of the opal trade — a bit of mining here and there, but mostly buying and selling as a dealer.

Mike Poben underground in a Coober Pedy claim circa 1987.(Supplied: Mike Poben)

His fortunes had always gone up and down with the market.

After being out of the game for a few years, Mike started making regular trips back to Lightning Ridge in 2013. The New South Wales town is one of the premier opal sites in the world.

On one of these visits, a pair of miners turned up at his door offering him some rough opal. Mike bought a few bags of these, known as “skin shells”: ancient sea shells that have turned into opal.

The first bag was mostly junk. But inside the second bag, Mike found a small fragment, about as big as the joint of his middle finger.

A blue and pink opal rock next to a gold coin and a ruler, which reads just over two centimetres length.
A photo of the opal the day after it was found, with a coin for scale.(Supplied: Mike Poben)

When he turned it over, he saw two small fan-shaped ridges and a vein of blue-green opal. As he looked at the piece through his magnifying glass, the hair started rising on the back of his neck.

“I think I was shocked, first of all … something in the back of my head said tooth,” he said.

“Opalised jawbone with teeth are rare as rocking horse shit … you just don’t find them.”

Mike didn’t know it at the time, but this small discovery in an unassuming bag of dirt and opals would change his life, and what we know about prehistorical life on the Australian continent.

The origins of opals

Opals come in a variety of shades and types. There are conventional gemstones, the polished orbs of colour usually displayed in shop windows.

Opals on display in a Coober Pedy showroom
Opals are prized around the world for their brilliant colour.(Supplied: James Jooste)

But there are also opalised fossils. These form under certain conditions when silica fills in the gaps left by bits of bone or shell buried deep beneath sedimentary rocks, forming opals that take the shape of the animals buried there.

A geological quirk means some of the richest veins of the most valuable opals in the world — black opals — are found around Coober Pedy, in South Australia, and Lightning Ridge.

These towns are surrounded by millions of holes in the ground, some that extend down hundreds of feet, dug by hand or rudimentary machinery by prospectors looking for the precious stones.

The modern Gulf of Carpentaria is the last remnant of a shallow inland sea that once covered most of eastern Australia about 100 million years ago.

Back then, the Australian continent sat 60 degrees south of where it is today, and Lightning Ridge was almost coastal real estate.

The dry and dusty region of today was once within the catchment of rivers and lagoons that drained into this sea, and the area would have been covered with densely vegetated, lush forests.

Millions of years later, what these great ancient seas have left behind is a strange sort of aquatic spirit in Coober Pedy and Lightning Ridge.

Mounds of dirt cover vast tracks of flat desert red sand across the horizon
Coober Pedy is famous for opal mining and has up to three million drill holes dotted across its opal fields.(Supplied: Justin Lang)

Walking around these desert towns, completely cut off from any open water, you will hear frequent references to the anatomy of sea creatures, like sharks teeth, sea shells, and cuttlefish bones.

Mike cherished the two little fossil fragments he found — two pieces of the same jawbone, richly coloured with veins of opal, brought up from deep underground and broken apart in the mining process.

They were almost separated forever, and Mike brought them back together and added them to the collection of his personal favourites.

“I can’t tell you how many times I’ve pulled those [opals] out of their hiding place and looked at them like at three o’clock in the morning,” he said.

After a few years of wondering about the opalised teeth in his private collection, his curiosity got the better of him.

No-one could seem to give him an answer for what they were, or what creatures they belonged to.

So Mike decided to get a professional opinion, someone who might know their origin and their value.

The paleontologist investigates

Mike’s networks eventually yielded a name — Phil Bell, a paleontologist with a penchant for walking around barefoot in the blistering heat of northern New South Wales, the region where he specialises as a researcher.

Dr Bell and an Italian colleague, Federico Fanti, met with Mike at a hotel room on a particularly hot day to look over some of his collection.

As opals are so valuable, these appraisals can be a delicate game, with neither side wanting to show too much interest and tip their hand.

Mike showed the pair a few of his other pieces, with little interest. But he saved the best for last — the two opalised teeth wrapped delicately in tissue paper.

“I knew something was up because both of them looked at the two pieces [of jawbone] for 45 minutes. They swapped them [back and forth,]” he explained.

Three men sitting at a table inspecting a piece of opal.
Paleontologists Phil Bell and Federico Fanti inspected the opalised jawbone with Mike Poben in a Lightning Ridge hotel room for the first time in August 2015.(Supplied: Jenni Brammall)

Under the table lamp in the cool, air-conditioned room, Dr Bell knew right away that these opals, flashing with blues and pinks, were unique.

“It was still kind of dirty [and] still had a lot of rock adhering to the surface of it,” he recalled.

“I saw not only the beautiful colour in these two pieces of bone, but also the teeth.

At this point, Mike could easily have cashed in for thousands of dollars with a reputable dealer. He could have used the money, and if he was looking for the highest bidder, he’d likely find one overseas.

Dr Bell knew these opals were something special, and he feared they may disappear into a private collection, never to be seen again.

So he and his colleague measured and photographed the specimen. They sketched the teeth and memorised their shapes and size.

From there, Dr Bell began scouring museums around the world, comparing the jawbone to other fossil records, hoping to find a match.

A photo of two opal fossil fragments with blue and green colouring and fan-shaped teeth prominent to the right.
The two opal fragments seemed to fit together and had similar colours running throughout.(Supplied: Robert A. Smith)

It was two years until everyone who had been in that hotel room finally learned the truth.

“To be honest, I feel overwhelmed now just talking about it,” Mike said, reflecting on the search years later.

“It’s a new species. They have proved beyond scientific doubt that it’s a previously undiscovered animal — a new Australian dinosaur.”

Friendly little creatures from the Cretaceous

The species that furnished Mike with the opalised jawbone were dog-sized herbivores, probably between one metre and two metres in length.

They likely travelled in herds, picking at the low branches and eating plants that grew around the freshwater lagoons of the region. Some of the species had a kind of beak on the lower jaw.

They now also have a full scientific name, inspired by Mike: Weewarrasaurus pobeni.

A computer illustration of small dinosaurs roaming a wetland area.
Weewarrasaurus pobeni were small, dog-sized herbivores who roamed in herds around ancient Australia.(Supplied: James Kuether)

“I mean, I had two years to think about it,” Mike said.

“I looked at the broader region and [it] was Weewarra. And I knew the source [of that word] was lizard.”

“I thought, ‘Oh, gee, that’s got a nice ring to it. It kind of rolls off the tongue.

“And the pobeni just comes from Poben, with an ‘i’ on the end.”

The jawbone never ended up in an overseas collector’s trophy case, either. What Dr Bell didn’t realise on their first encounter in that hotel room was how much of a fossil geek Mike really is, and how strongly he felt the fossils needed to stay where they were found.

“They said [to me] we’re hoping that you’ll donate it to the museum,” Mike explained. “And I knew right away it was the right thing to do.”

So the opalised Weewarrasaurus pobeni teeth now live at the Australian Opal Centre in Lightning Ridge.

“Mike appreciates it so much that he doesn’t want it on his mantelpiece like so many collectors do. He sees that the true value of it, which is to all Australians; it’s to the entire world, really.

“So people can now go and see that jaw [at the museum] and it’s there for everyone to appreciate and hopefully get a little bit of the thrill that Mike and I got in laying our eyes upon this thing for the first time.”

And Mike is one of the few people in the world who knows what it feels like to have a dinosaur named after you.

“Every time I see it written I’m gobsmacked that my surname is attached to the creature,” he said.

“I don’t want to get philosophical, but it’s added meaning to my life in ways that I never thought it would.”



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