Australia is famous for producing nightmare-inducing animals, from birds that break and enter to deadly funnel-weaving spiders. So it should be no surprise that the extinct marsupial lion (Thylacoleo carnifex), the biggest meat-eating mammal ever known to roam Australia, is one of the gnarliest animals in the fossil record.
For the first time, scientists have reconstructed the entire skeleton of this 200-pound marsupial, which died out some 46,000 years ago. The results, published Wednesday in PLOS One, are based on newly discovered fossils and comparisons to extant relatives.
Authored by paleontologists Roderick Wells of Flinders University and Aaron Camens of the South Australia Museum, Adelaide, the study reveals an idiosyncratic hunter with retractable claws, semi-opposable digits, bladed teeth, a heavily-muscled tail, a cat-like skull, and the body of a beefed-up Tasmanian devil.
All those unique adaptations added up to make T. carnifex a formidable ambush predator and expert climber, with gripping skills similar to a koala. Its hunting strategy may have involved perching on tree boughs or cliff walls and using gravity as an assist to tackle unsuspecting prey, according to previous research. Because of this, the species has sometimes been compared to the Australian “drop bear” urban legend starring a bloodthirsty koala cryptid that kills people by falling on them from above.
Wells and Camens outline the predator’s killing skills in gruesome detail—especially its bite, which was “unparalleled amongst extant carnivores.”
“We envisage T. carnifex dismembering a carcass by piercing with the lower incisors against the resistance of the uppers,” the team said. “A thrust with the honed puncturing tip of the paired lower incisors [...] may have been employed to sever the spinal cord at the neck, sever tendons, or cause massive trauma to a struggling prey during capture.”
This killer bite wasn’t the only weapon in the marsupial lion’s arsenal. T. carnifex was also built like a Mack Truck, differentiating it from the sleek big cats that it’s nicknamed for (the marsupial lion was not a close relative of lions, but was about the same size as modern lionesses). Lions are built for speed and endurance, but marsupial lions were bodyslammers that leveled prey like Diprotodon, the biggest marsupial known to walk planet Earth.
“The powerful forelimbs equipped with grasping hands and slashing first digit would amply serve to both to restrain a victim or a carcass,” Wells and Camens said in the study. “Their ability to anchor the hind quarters using the tail as a brace freed the [limbs and hands] to hold, lacerate, or eviscerate struggling prey and/or to hold a carcass while severing limb elements, flesh, and hide with a rearwards pull of the shoulders, neck, and thorax.”
Given how utterly badass these predators sound, it’s a wonder they went extinct. The reasons why T. carnifex died out are not fully understood, but likely culprits are long-term climate change and anthropogenic pressures, as humans arrived in Australia at least 65,000 years ago.
Though the marsupial lion is long gone, its legacy as one of Australia’s most terrifying killing machines—a competitive category—lives on.
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