By Liam Mannix
About 120 million years ago, in the early Cretaceous period, Victoria was in forever winter. Our continent had drifted down towards the very bottom of the world. Its southern coast was a vast river in a rift valley as wide as the Nile, the banks thick with pine trees and the frigid waters teeming with fish.
Among the pines, dinosaurs hunted. Bird-footed southern raptors fossicked in the shallows for fish, and mid-sized megaraptorids with curved claws and toothy grins.
This picture has always seemed, to paleontologists, incomplete. There are many prey animals represented in the fossil records – but no Tyrannosaurus rex.
An artist’s depiction of Victoria 120 million years ago. On the left is a carcharodontosaur, a unenlagiinae (centre) and a megaraptor (right).Credit: Museums Victoria / Jonathan Metzger
We are missing a super-predator.
A new discovery by a team of volunteers and scientists published Thursday takes a big step to solving that riddle by unearthing tantalising first evidence a large predatory dinosaur, never before seen here: carcharodontosauria.
In other parts of the world, carcharodontosaurs are true apex predators, reaching up to 13 metres in length. But not ours. Victoria’s new carcharodontosaur is tiny: just two to four metres long.
“They weren’t in Australia. Until now. And not in a way you’d expect,” said Tim Ziegler, the collection manager for vertebrate palaeontology at the Museums Victoria Research Institute.
In a striking two-part finding published on Thursday in the Journal of Vertebrate Paleontology, the team shows evidence of diminutive carcharodontosaurs– and huge seven-metre long megaraptorids, typically a smaller creature.
Together, that suggests Australia’s dinosaur ecosystem was “upside down”, said Ziegler.
“It shows in Australia something unique, different to anywhere else in the world, may have happened,” he says. “We overturn the ecology.”
Tim Ziegler, collection manager, vertebrate palaeontology, Museums Victoria Research Institute and (left) Jake Kotevski, PhD candidate, Museums Victoria Research Institute.Credit: Nadir Kinani / Museums Victoria
An ancient world, upside down
Popular and scientific views of dinosaurs have been shaped largely by North American discoveries – where near-complete tyrannosaur, stegasaur and diplodicus skeletons were pulled from the ground near the turn of last century.
Australia long seemed a dinosaur backwater. “What we had were survivors, relics. Maybe they’d dispersed around the world and found a refuge, a little land before time, down here,” said Ziegler.
But a “blossoming of discovery” in places like India, Thailand and here is remaking that picture, said Ziegler.
A megaraptor.Credit: Museums Victoria
It is becoming clear the southern hemisphere had its own dinosaur ecology – and it was unique.
Australia’s carcharodontosaur is diminutive. And our megaraptorids were, perhaps, the apex predators.
“We see an animal that is a chase predator. This is an animal that is adapted to rapid movement, rapid changes in direction. Their weapon of choice is grasping, holding, clutching those small fast-moving dinosaurs,” said Ziegler.
Why this inversion? Perhaps megaraptorids evolved first and got big – and their size allowed them to out-compete carcharodontosaurs. Perhaps Victoria lacked the big plant-eating dinosaurs that carcharodontosaur likes to prey on.
A carcharodontosaur.Credit: Museums Victoria
Or perhaps the new fossils are from a juvenile. It is hard to be definitive when the evidence comprises two small pieces of bone from 120 million years ago.
A dinosaur super-sleuth
The fossils are likely from creatures that died near a river, their bodies tumbling down the banks before the rushing waters piled sediment over them.
Over millions of years that sediment hardened into the sandstone that now make up the cliffs around Inverloch, where the megaraptorid fossils were discovered in 2022 and 2023 by Museums Victoria volunteer Melissa Lowery.
Twin Reefs fossil site in Bunurong Coastal Reserve, where some of the fossils were found.Credit: Museums Victoria / John Broomfield
Lowery regularly walks the beaches of Inverloch, looking for tiny hints of preserved bone jutting from the exposed limestone cliffs.
Other volunteers describe Lowery as a dinosaur-bone ‘super-sleuth’. “I could swear she can smell the stuff,” said long-time colleague Tom Rich, a co-author on the paper.
The carcharodontosaur fossils were hiding in plain sight. One small bone had been found by Rich’s wife, Pat, on the Bass Coast in 1987 but never conclusively identified; another was found in the Otways in 2004. Both sat in the museum’s drawers until Monash University PhD student Jake Kotevski came across it in 2022.
“There’s so much collection and not enough research, or the right person wasn’t there,” he said.
But Kotevski is the right person. He grew up watching Jurassic Park. He has a T. rex tattoo. His dream has always been to find one of the giant predators he is sure must have once roamed Victoria.
A fossilised vertebrae from a megaraptor.Credit: Nadir Kinani / Museums Victoria
He was drawn to the two bones – a right and left ankle – because they looked nothing like the dinosaurs already found here. Could they be from a super-predator?
Kotevski spent three months comparing his bones with the ankles of every other published dinosaur. Finally, he flipped to a carcharodontosaur found in Thailand in 2019.
“It looked effectively like a mirror of mine. It was almost a one to one. My heart skipped a beat,” he said.
Small carcharodontosaurs and huge megaraptorids. Does this solve the super-predator mystery? No, but it brings us a step closer.
“We just need to find more,” says Kotevski. “I think the mystery goes on.”
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