Paleontologists have identified peptide markers for three species of extinct Australian megafauna — a hippo-sized wombat, a giant kangaroo, and a marsupial with enormous claws — opening the way for research which could help us understand how a series of unexplained extinctions of megafauna 50,000 years ago happened, and if humans were responsible.
Palorchestes azael. Image credit: Nellie Pease / CABAH / CC BY-SA 4.0.
“The geographic range and extinction date of megafauna in Australia, and potential interaction with early modern humans, is a hotly debated topic,” said University of Vienna’s Professor Katerina Douka.
“The low number of fossils that have been found at paleontological sites across the country means that it is difficult to test hypotheses about why these animals became extinct,” added University of Algarve’s Dr. Carli Peters.
“Zooarchaeology by mass spectrometry (ZooMS) could increase the number of identified megafauna fossils, but only if collagen peptide markers for these species are available.”
Analyzing the peptides found in samples of collagen allows scientists to distinguish between different genera of animals, and sometimes between different species.
Because collagen preserves better than DNA, this method can be applied successfully in tropical and sub-tropical environments where DNA is unlikely to survive.
But most reference markers are for Eurasian species that never lived in other parts of the world.
This research develops new reference markers for an Australian context, allowing scientists to glean more information from Australia’s fragmented fossil record.
“Proteins generally preserve better over longer timescales and in harsh environments than DNA does,” Dr. Peters said.
“This means that in the context of megafauna extinctions, proteins may still be preserved where DNA is not.”
The researchers chose to study three species which could be particularly valuable for understanding megafauna extinctions: Zygomaturus trilobus, Palorchestes azael, and Protemnodon mamkurra.
Zygomaturus trilobus and Palorchestes azael are from families of animals that went completely extinct during the Late Quaternary, while Protemnodon mamkurra survived long enough that it could potentially have overlapped with humans arriving in Tasmania.
The scientists previously dated the fossilized bones of the species to beyond 43,000 years ago.
“Zygomaturus trilobus was one of the largest marsupials that ever existed — it would have looked like a wombat the size of a hippo,” Professor Douka said.
“Protemnodon mamkurra was a giant, slow-moving kangaroo, potentially walking on all fours at times.”
“Palorchestes azael was an unusual-looking marsupial that possessed a skull with highly retracted nasals and a long protrusible tongue, strong forelimbs, and enormous claws.”
“If the early modern humans who entered Sahul — the paleocontinent that connected present-day Australia, New Guinea and Tasmania 55,000 years ago — came across them, they would have certainly got a big surprise.”
The authors ruled out any contaminants and compared the peptide markers they found to reference markers.
The collagen in all three samples was well-preserved enough for the team to identify suitable peptide markers for all three species.
Using these markers, the paleontologists were able to differentiate Protemnodon from five living genera and one extinct genus of kangaroos.
They were also able to distinguish Zygomaturus and Palorchestes from other living and extinct large marsupials, but they couldn’t differentiate the two species from each other.
This is not unusual with ZooMS, since changes in collagen accumulate extremely slowly, over millions of years of evolution.
Unless further research allows for more specificity, these markers are best used to identify bones at the genus level rather than the species.
However, the ability to tell apart genera from more temperate regions of Sahul does present an opportunity to try to identify bones found in more tropical areas, where closely-related species — which are likely to have similar or even the same peptide markers — would have lived. DNA rarely preserves over time in these regions.
“By using the newly developed collagen peptide markers, we can begin identifying a larger number of megafauna remains in Australian paleontological assemblages,” Dr. Peters said.
“However, there are a lot more species for which collagen peptide markers still need to be characterized.”
“Two examples would be Diprotodon, the largest marsupial genus to have ever existed, and Thylacoleo, the largest marsupial predator.”
The team’s results appear in the journal Frontiers in Mammal Science.
_____
Carli Peters et al. 2025. Collagen peptide markers for three extinct Australian megafauna species. Front. Mamm. Sci 4; doi: 10.3389/fmamm.2025.1564287
