Fossil collagen fingerprints reveal that the carnivorous marsupial Thylacoleo carnifex, long likened to the mythical “drop bear,” lived in Australia until about 40,000 years ago. Protein analysis places Thylacoleo closer to modern koalas and wombats than to other living mammals. The researchers applied the method to several extinct megafauna, showing the technique’s power to refine evolutionary trees and inform studies of late Pleistocene extinctions.
Real-life ‘Drop Bear’: Fossils Show Carnivorous Marsupial Related to Koalas Lived Until ~40,000 Years Ago
Fossil collagen fingerprints reveal that the carnivorous marsupial Thylacoleo carnifex, long likened to the mythical “drop bear,” lived in Australia until about 40,000 years ago. Protein analysis places Thylacoleo closer to modern koalas and wombats than to other living mammals. The researchers applied the method to several extinct megafauna, showing the technique’s power to refine evolutionary trees and inform studies of late Pleistocene extinctions.
08:42 PM, 11/12/2025Science
Fossils link the legendary “drop bear” to a real marsupial predator
New research shows that a carnivorous marsupial with close affinities to modern koalas lived in Australia until roughly 40,000 years ago. The species, Thylacoleo carnifex — often called the “marsupial lion” — was part of a diverse Late Pleistocene fauna that disappeared during a major wave of extinctions.
Collagen fingerprints reveal evolutionary relationships
Researchers applied a novel protein-based technique that creates species-specific "fingerprints" from preserved collagen in fossil bones. By comparing collagen peptide sequences, the team reconstructed evolutionary relationships among extinct Australian megafauna and living marsupials.
The study, published in Proceedings of the Royal Society B, analyzed three well-known extinct taxa: Zygomaturus (a large herbivore resembling a 500 kg wombat), Palorchestes (a tapir-like plant-eater), and Thylacoleo carnifex (the carnivorous marsupial lion). The protein evidence indicates that Thylacoleo is more closely related to the modern koala and wombats than to any other living mammal group.
"The weight of evidence provided by the collagen peptide data favoured a close relationship between Thylacoleo (the so-called ‘marsupial lion’) and the koala, as part of a broader clade including wombats," the researchers wrote.
Context and implications
These carnivores thrived during the Late Pleistocene (roughly 126,000 to 40,000 years ago). Around 40,000–46,000 years ago many of the continent’s largest animals went extinct — Australia lost nearly 90% of terrestrial species heavier than about 44 kg — during a period that overlaps with human arrival. The drivers of this megafaunal decline remain debated, with climate change, human impact, or a combination of factors all considered possible contributors.
Beyond clarifying relationships among extinct species, the study demonstrates the power of collagen-based proteomics to build evolutionary trees from fossil material. The authors say broader application of this approach may help refine timelines of extinction and better pinpoint the environmental and ecological changes that accompanied them.
Next steps
Scientists hope to apply collagen fingerprinting to more specimens and regions to improve resolution on Pleistocene biodiversity and to test hypotheses about the causes and pace of the late Pleistocene extinctions in Australia.