New research suggests it was climate change—not human activity—that caused Thylacoleo carnifex, an Australian marsupial lion, to go extinct.
For millions of years, Thylacoleo carnifex ruled the forests of Australia, but this predatory species disappeared around 35,000 to 45,000 years ago. Humans first appeared in Australia around 60,000 years ago, leading scientists to wonder if humans were somehow responsible—not an outrageous suggestion, given our dubious track record on such matters.
New research led by paleontologist Larisa DeSantis from Vanderbilt University, with help from her colleagues at the University of New South Wales and University of Queensland, suggests these marsupial lions lost their habitat on account of climate change (the natural kind—not the human-induced version we’re witnessing today), leading to its eventual extinction. Humans, according to this research, had nothing to do with it. For once.
Thylacoleo is the largest carnivorous Australian mammal known, reigning as one of Australia’s most fearsome predators for 2 million years. These creatures were slightly bigger than modern leopards, but smaller than today’s African lions. Their jaws packed a tremendous punch, producing some of the strongest bite forces ever documented in a mammal.
DeSantis and her colleagues were able to show that Thylacoleo was an exclusive forest dweller, and not accustomed to open habitats, a conclusion reached by applying two different methods.
“Stable isotopes told us that Thylacoleo ate prey that resides in forests,” DeSantis explained to Gizmodo, while a 3D dental analysis of wear-and-tear on this creature’s teeth pointed to the same conclusion. “We determined,” she said, “that Thylacoleo was highly specialized on prey from forested environments and this would’ve made it more vulnerable to extinction with the long-term pattern of aridification that begin around 350,000 years ago.” These findings were presented by DeSantis and her colleagues at a recent meeting of the Society of Vertebrate Paleontology, and a formal science paper is forthcoming.
In addition to the chemical and dental analyses, a review of this animal’s physical characteristics suggests it was an ambush hunter, capable of launching itself at unsuspecting prey at close distances. Thylacoleo, the researchers say, was not built to chase speedy prey across vast, open landscapes.
As DeSantis pointed out, Australia began drying out some 350,000 years ago, a process that turned lush forests into open savanna. Thylacoleo, being highly adapted to forests, simply could not adjust to the loss of its habitat, becoming less effective at hunting over time. “This research,” she said, “helps demonstrate that even the fiercest predators can succumb to climate change.”
Study co-author Gilbert Price from the University of Queensland echoed these sentiments in a press release: “When you’re big and bitey, you can eat pretty much anything you want. But our findings show that even the top predators are no match for extreme climate change.”
“Marsupial lions were far more specialised than African lions. They even had a proportionately larger brain than African lions as well as large, uniquely formidable, large can-opener-like thumb claws,” Michael Archer, a paleontologist from the University of New South Wales, said in a statement. “What’s increasingly clear now is that it evidently survived the arrival of humans 60,000 years ago, but apparently not the profound impacts of a rapidly drying climate that undermined the survival of a range of megafaunal mammals in Australia.”
In terms of the study’s shortcomings, the authors admit that they only sampled specimens from New South Wales in Queensland. “Thus,” DeSantis told Gizmodo, “while we don’t have data from Western Australia, all 35 of our samples from eastern Australia suggest that Thylacoleo was a specialist on forest-dwelling prey.”
Interestingly, this now-extinct marsupial lion was a contemporary of the thylacine, more famously known as the Tasmanian tiger. This animal, which went extinct during the 20th century, was better able at adapting to Australia’s new and open habitats, which likely explains why it survived Australia’s aridification period while Thylacoleo could not. Thylacoleo carnifex had some impressive physical characteristics, but its highly specialized adaptations ultimately proved to be its undoing.