The research was led by Queensland Museum and included experts from a number of Australian universities including the University of Wollongong (UOW).

The team concluded that extreme environmental change was the most likely cause of the megafauna's extinction, and that humans alone could not be blamed.

Read more: Libraries and galleries to reopen, as NSW travel ban lifts from June 1

The fossils were discovered at an area near Mackay called South Walker Creek. It is the youngest megafauna site in northern Australia.

The findings, published in the open access scientific journal Nature Communications, outline how the successive loss of water flow, intensified drying, increased burning and vegetation change created the conditions to drive the extinction of at least 13 species of super-sized megafauna species, including five reptilian megapredators, a marsupial "lion" and the world's largest wombats and kangaroos.

Professor Anthony Dosseto from UOW's School of Earth, Atmospheric and Life Sciences helped analyse the discoveries made at the site. He said the team used a range of techniques to get robust ages on the megafauna fossils.

Queensland Museum palaeontologist Dr Scott Hocknull, who led the study, said there was still more research to come out of the site.

"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."

Professor Dosseto, founder of the Wollongong Isotope Geochronology Laboratory, said the findings challenged the theory that human hunting largely drove the extinction of Australian megafauna.

"Our study shows that Australia megafauna was alive and well in Queensland later than previously thought...these new results show that humans alone didn't drive megafauna to extinction; climate and environmental change was also a big driver," he said.

One highlight from the site was the discovery of the remains of a kangaroo that stood 2.5 metres tall with an estimated mass of 274 kg, making it the largest known kangaroo of all time.

Our COVID-19 news articles relating to public health and safety are free for anyone to access. However, we depend on subscription revenue to support our journalism. If you are able, please subscribe here. If you are already a subscriber, thank you for your support.