Researchers optimistic after megafauna dig

08 December 2016

The 'buckets of bones' discovered at Lancefield, north of Melbourne, will offer clues to the cause of Australia's megafauna extinction.

Having captured the popular imagination, Australian megafauna such as giant kangaroos, wombats and marsupial lions, which once wandered Australia’s plains and forests, are equally intriguing to scientists. These giant marsupials raise questions as to how they lived, where they roamed and why they became extinct.

As part of the Extinct-Lancefield Megafauna Festival, an open day attracted over 800 visitors to Lancefield swamp; one of the richest deposits of megafauna fossils in Australia.

Coinciding with the festival, Deakin taphonomist Sanja van Huet led a week-long dig to discover answers to these megafaunal mysteries.

Over the week, 25 volunteers and researchers collected megafauna fossils, dated at 60,000 years old.

Dr van Huet, from Deakin's School of Life and Environmental Sciences, led a multidisciplinary team that included archaeologists, palynologists (fossil pollen), macro and micropalaeontologists, isotope specialists, geologists, dating and sonar resonance experts, who are all trying to find the cause of the accumulation of fossil material at the site.

“We have buckets of bones to go through,” Dr van Huet said.

“Over the past century, scientists have formally identified the bones from approximately 24 species from the swamp, but we think we will be able to add two or three more animals that have previously been unknown from this site.”

Sonar resonance (measuring how fast vibrations travel through different layers under the surface) was used to locate undiscovered bones.

Given the area is a swamp, the team had to organise water pumps to temporarily remove groundwater from the digging site.

"Scientists estimate that there could be more than 10,000 animals buried in the swamp. Although quite a few of them have been dug up, there seems to be many more still buried," Dr van Huet said.

"There are lots of bones buried in the swamp which are from an extinct species of kangaroo. These fossil kangaroos were twice the mass of modern ‘roos.

"There were also Diprotodon, a wombat-like animal the size of a rhinoceros, and Thylacoleo, the marsupial lion. Thylacoleo is the largest known carnivorous marsupial in Australia. It had enormous slicing molar teeth for cutting up its prey."

One of the most exciting finds of the week was a possible claw that may be from a carnivore. Researchers are enthusiastic, but will wait for the formal identification to confirm the actual species.

Dr van Huet said there was plenty of conjecture about why the megafauna died out, with scientists still debating climate change, human interaction, disease or multiple factors as the cause.

"But I'm most interested in how and why they were buried here. It's long been believed that these animals were ‘tethered’ to a waterhole during drought conditions and then died once their food supply ran out," she said.

"Further work is suggesting other factors were involved. The new dig has uncovered fossil material mixed in with pebbles, indicating that the bones may have been washed in after an extreme weather event such as a 100-year flood.

“Over the week, we discovered numerous teeth belonging to Macropus titan, or giant kangaroo. The teeth were mixed up with highly rounded quartz pebbles, supporting the theory that many of the animals were washed into the swamp through a flood or water flow, probably during an extreme rainfall event.

“We are hoping to undertake a four-week dig at the site in 2017. This could be the start of a five-year multidisciplinary project, the biggest of its kind in Australia. We may finally put together a comprehensive idea of what happened."

The dig was attended by scientists from Deakin, La Trobe and Federation Universities in Victoria. Other collaborators involved with the project are from Monash University, University of Adelaide and several independent researchers.

By Deakin Research

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'The new dig has uncovered fossil material mixed in with pebbles, indicating that the bones may have been washed in after an extreme weather event such as a 100-year flood.'

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'The new dig has uncovered fossil material mixed in with pebbles, indicating that the bones may have been washed in after an extreme weather event such as a 100-year flood.'

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