Before there were dinosaurs, there was Tasmaniosaurus.
Tasmania is not famous for dinosaur digs but despite their absence in the fossil record, Tasmania was home to these creatures and palaeontologists can infer what they were like from Victorian fossils.
However, there is evidence of creatures that crawled around the ancient land just before the dawn of the dinosaurs.
Extraordinary fossils of an ancient reptile – Tasmaniosaurus triassicus — were uncovered in Knocklofty Reserve in the suburb of West Hobart and described to the world in 1978.
“I think it is one of the coolest fossils to have been discovered in Tasmania,” palaeontologist Tim Ziegler told ABC Hobart’s Kylie Baxter.
The ancient reptile lived around 250 million years ago, during the Triassic when Tasmania was part of a supercontinent called Pangea.
Why was Tasmaniosaurus so cool?
Tasmaniosaurus looked like a “cross between a dinosaur and a crocodile”, Mr Ziegler, who is the collections manager of vertebrate palaeontology at the Melbourne Museum, said.
“It’s an animal that lived on a sort of separate offshoot of that bushy tree of life to dinosaurs and it’s living in a pre-dinosaur world.
“It’s got a mouth full of serrated teeth and a skull that’s probably about as long as your outstretched hand.”
The Tasmaniosaurus used its serrated teeth to hunt down prey — this likely included ancient amphibians called labyrinthodonts which Mr Ziegler described as “the salamander of your nightmares”.
Fossils of labyrinthodonts have also been found in West Hobart.
But back when labyrinthodonts and Tasmaniosaurus were roaming around, the land looked very different.
Knocklofty Reserve is now celebrated for its beautiful eucalyptus, wildflowers and birds – but 250 million years ago, flowering plants and birds were yet to evolve.
“That land [was] a series of lakes and ponds and waterways and these are the animals that are living around and in that water,” Mr Ziegler said.
What about Tasmanian dinosaurs?
Palaeontologists can get hints as to what Tasmanian dinosaurs would have been like by studying Victorian fossils.
Most of the Victorian dinosaur fossils from the early cretaceous, between 125 and 100 million years ago.
“Tasmania, Victoria and even other continents in the southern hemisphere were connected up at this time,” Mr Ziegler explained.
Pangea had broken up by this time and our part of the world was part of another supercontinent called Gondwana.
“The kind of dinosaurs that were living in Victoria generally are fairly small and active,” Mr Ziegler said.
Meet the ‘anti-Tyrannosaurus rex’
(Museums Victoria: Benjamin Healley)
Mr Zeigler described an apex predator called Australovenator, or the “southern hunter”, as having been the “anti-Tyrannosaurus”.
“Instead of being giant bodied and maybe a bit slow with a huge head and tiny arms it can’t even scratch itself with [like Tyrannosaurus rex], Australovenator is this lithe, agile, really pacey predator,” he said.
It was half the size of Tyrannosaurus rex – which still meant it would have measured at a terrifying 6 metres long — and had a small head.
The southern hunter’s real weapons would put T.Rex to shame as it had “enormous grasping arms and these really terrifying curving claws,”
It used these claws to hunt other dinosaurs including swamp wallaby sized creatures called bird footed dinosaurs, or ornithopods.
There were several of these small plant eating species darting around the forests of the southern hemisphere.
Surviving the Antarctic
The land that is now Australia’s south-east was far further south “at least 60 to 70 degrees south in the southern polar circle”, so southern species had to adapt to long polar winter.
The earth was warmer then, but life at the poles would still have been a challenge.
“Many of them were actively warm blooded … they could regulate their body temperature and their metabolism,” Mr Ziegler said.
“So maybe, come the cold, wet, very dark polar winters of the early Cretaceous, they just got on with it and worked a bit harder.”
“They may have migrated to other parts of Australia, up north to Queensland or even around through Antarctica to South America.”
Despite not having a dinosaur studded fossil record, Tasmania is the proud home to over 350 species of living dinosaur in the form of modern birds – the only dinosaurs to survive the mass extinction 65 million years ago.
