An international team of paleontologists has proposed that an extinct animal called the marsupial lion (Thylacoleo carnifex) hunted in a very unique way – by using its teeth to hold prey before dispatching them with its huge claws.
Reconstruction of the marsupial lion (Thylacoleo carnifex). Image credit: Mauricio Antón.
The marsupial lion was a predatory marsupial that inhabited Australia during the Pleistocene epoch from about 2.5 million years ago until as recently as a few tens of thousands of years ago. It was the continent’s top predator at the time of human arrival 50,000 years ago.
The animal was first described from fossils in 1859 by English paleontologist Sir Richard Owen.
It was 5 feet (1.5 m) long, 2.5 feet (75 cm) tall, and weighed between 175 and 220 pounds (80-100 kg) – making it the largest carnivorous marsupial to have ever lived on Earth.
As its name suggests, the marsupial lion has long been presumed to be a cat-like predator, despite lacking large canine teeth – instead it had large, protruding incisors that have been suggested to be canine substitutes.
The prehistoric creature was a powerful marsupial but, as other paleontologists have noted, it had limbs of different proportions to a lion, suggesting it was not a fast.
It also sported a very large claw on its hand, similar to the dew claw of cats but of a much bigger size, with a bony sheath foisted on a mobile first digit (thumb).
Dr. Christine Janis from the University of Bristol and Brown University and her colleagues from the University of Malaga looked at the elbow joints of a large number of living mammals.
This showed a strong association between the anatomy of the humerus (upper arm bone) where it articulates with the forelimb and the locomotor behavior of mammals.
Animals more specialized for running (like a dog) have a joint indicating movement limited for back and forwards, stabilizing their bodies on the ground, while animals more specialized for climbing (like a monkey) have a joint that allows for rotation of the hand around the elbow.
Modern cats, which (unlike dogs) use their forelimbs to grapple with their prey, have an elbow joint of intermediate shape.
Hand of the marsupial lion, containing giant claw. Image credit: Borja Figueirido et al.
“If the marsupial lion had hunted like a lion using its forelimbs to manipulate its prey, then its elbow joint should have been lion-like, Dr. Janis said.
“But, surprisingly, it a unique elbow-joint among living predatory mammals – one that suggested a great deal of rotational capacity of the hand, like an arboreal mammal, but also features not seen in living climbers, that would have stabilized the limb on the ground (suggesting that it was not simply a climber).”
The team proposed that this unique elbow joint, in combination with the huge ‘dew claw’ on a mobile thumb, would have allowed the marsupial lion to use that claw to kill its prey. In contrast the large incisors were blunt.
While the animal had massive shearing teeth in the back of its jaw, the incisors appear to have functioned better for gripping than for piercing flesh in a killing bite.
The scientists concluded that, unlike a real lion, which holds its prey with its claws, and kills it with its teeth, the marsupial lion – unlike any living predator – used its teeth to hold its prey, while it dispatched it with its huge claws.
The team’s research was published in the journal Paleobiology.
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Borja Figueirido et al. Ecomorphological determinations in the absence of living analogues: the predatory behavior of the marsupial lion (Thylacoleo carnifex) as revealed by elbow joint morphology. Paleobiology 42 (3): 508-531; doi: 10.1017/pab.2015.55
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Marsupial Lion Thylacoleo carnifex Had Unique Hunting Style, Paleontologists Say
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