Mysteries of megafauna extinction unlocked

Megafauna mysteries unlocked
Extinct giant marsupial diprotodon jaw bone found at South Walker Creek in Mackay, north Australia. IMAGE: Queensland Museum

University of Melbourne and Queensland Museum palaeontologists have today announced the discovery of new extinct Australian megafauna that lived until 40,000 years ago in tropical northern Australia.

The research has come out of an area near Mackay called South Walker Creek, which is the youngest megafauna site in northern Australia, and once home to at least 16 species of megafauna.

Led by Queensland Museum palaeontologist and University of Melbourne honorary, Dr Scott Hocknull, the team found that extreme environmental change was the most likely cause of extinction, not humans.

"The megafauna at South Walker Creek were uniquely tropical, dominated by huge reptilian carnivores and mega-herbivores that went extinct around 40,000 years ago, well after humans arrived onto mainland Australia," Dr Hocknull said.

"We cannot place humans at this 40,000-year-old crime scene, we have no firm evidence. Therefore, we find no role for humans in the extinction of these species of megafauna.

"Instead, we do find that their extinction is coincident with major climatic and environmental deterioration both locally and regionally, including increased fire, reduction in grasslands and loss of freshwater. Together, these sustained changes were simply too much for the largest of Australia's animals to cope with."

The South Walker Creek site was the stomping ground for a diverse range of megafauna including several new species, which are yet to be formally described.

Dr Hocknull said some of the highlights from the site included the discovery of the remains of the world's largest kangaroo at 2.5 metres tall and an estimated mass of 274kg, this makes it the largest kangaroo of all time.

"While the rest of the world had giant carnivores like sabre-toothed cats, bears and hyenas, Australia's predators were mostly giant reptiles, including an extinct freshwater croc around seven metres long, a relation to the modern salt water crocodile and a land-dwelling crocodile," he said.

"There were also two giant lizards including a six-metre long lizard called Megalania and another giant lizard, similar in size to the Komodo Dragon."

The fossils were discovered in 2008 by the Barada Barna people during a cultural heritage clearance at the South Walker Creek site, which is operated by BHP Billiton Mitsui Coal. The site is located 40 kilometres west of Nebo and through a partnership with Queensland Museum Network, there has been a systematic excavation since 2008 which has revealed spectacular never-before-seen megafauna fossils ranging from minute fish scales to colossal limb bones.

"The Board of Directors from the Barada Barna Aboriginal Corporation are extremely excited that we have found the Megafauna within our traditional country," a Barada Barna Aboriginal Corporation spokesperson for the Board of Directors said.

"The Barada Barna people have an immensely proud history dating back to our first encounters with Ludwig Leichhardt in 1845 on the banks of Cherwell Creek and having discovered Megafauna only enriches our history within this region.

"The team that discovered these finds back in 2008 had no idea of how great a discovery it was, with the help of Queensland Museum we have discovered more and more animals from that time."

Dr Hocknull's paper is the culmination of more than a decade of work with a number of scientists including the University of Adelaide, Griffith University, Southern Cross University, University of Queensland, Australian National University and University of Wollongong.

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