Palaeontologists have solved a 200-year-old mystery about how the bones of ancient marsupial lions ended up inside the Wellington Caves of central western New South Wales.
Europeans first found a rich collection of vertebrate fossils at the site in the 1820s, raising questions about how they ended up there.
In a recent excavation mission, a team from Flinders University discovered something new as they uncovered the bones of two adults and one young marsupial lion, or Thylacoleo carnifex.
"In some of the bones we found in this dig there are spiral fractures, which means the bones were broken at or near the animal's death," project lead Aaron Camens said.
Weighing up to 164 kilograms, the marsupial lion was the largest mammal predator ever found in Australia and preyed on other megafauna such as the diprotodons between 2 million and 46,000 years ago.
Dr Camens said bone fracture patterns indicated that many of them had fallen through a hole in the cave ceiling and remained buried there, waiting to be discovered.
"The larger animals will actually fall in through what's called a solution pipe in the ceiling of the chamber, and that's often only a metre or less wide," he said.
Thylacoleo carnifex is one of several species found in the Wellington Caves, which is known as Australia's "birthplace of palaeontology" — the first location where Europeans found megafauna fossils.
Discovery 'the tip of the iceberg'
Diana Fusco, a leader in Wellington Cave research, said while palaeontologists like herself had been excavating them for centuries, the caves still held many mysteries.
Dr Fusco said while we now know some megafauna fell into the caves, questions remained on how so many other fossils ended up there in the first place.
"Every time you lift the lid on research you tend to come up with more questions than what you started out with," she said.
"What we know is still just the tip of the iceberg; there's so much more information we can extract from these caves."
Digging expeditions have also come back with several traces of megalania, a hulking predatory lizard which could grow up to 7 metres long.
Among the massive remains, palaeontologists have also detected tiny footprints belonging to rat-like creatures as well as dunarts, which still exist today.
Dr Fusco said these fossil records held the key to understanding how animals responded to the threat of climate change.
Her research suggests slow, gradual extinctions interspersed with mass-extinction events and climate change forced rapid adaptation and population shift.
She said this could give a clue on how climate change was impacting ecosystems in the present day, and what we could expect to see in the future.
"The past is the best predictor of the future," Dr Foscu said.
"It's such an amazing resource that we just want to keep going and seeing what else we can uncover."
