CHICAGO, Oct 1 (Reuters) - The saber-toothed cat Smilodon, one the fiercest predators to roam the Ice Age, had a fairly wimpy bite, Australian researchers said on Monday, but this powerful killing-machine was no pussycat.
Researchers at the University of New South Wales and the University of Newcastle compared Smilodon's bite strength to another fearsome feline, the modern lion, using a computer model.
"Bite strength has long been a contentious issue in Smilodon," said Stephen Wroe of the University of New South Wales in Sydney, whose study appears in the Proceedings of the National Academy of Sciences.
Smilodon was one of the most powerfully built feline predators to ever prowl the Earth.
Wroe said early investigators had concluded Smilodon's bite was weak, but later investigators believed it was strong. Wroe and colleagues sought to put the matter to the test.
They used data from CAT scan X-rays of lion and Smilodon skulls to build sophisticated programs that could compare the mechanics of each cat's bite.
What they hoped to gain was a better understanding of how Smilodon killed its prey.
Wroe said lion skulls are built to withstand great forces as they bite animals that "are trying very hard to escape."
When the researchers subjected the digital Smilodon skull to these same forces, it showed much higher stress.
"If Smilodon bit into prey that was struggling wildly -- as can a lion -- it would have risked serious injury and perhaps even breakage of its own skull and teeth," he said in an e-mail.
Smilodon's mechanical performance was so poor compared with a lion that the researchers believe it could only have bitten prey that it had pinned down first. And that was the real source of its might.
"Its body was immensely powerful," Wroe said, noting that Smilodon's build was more bear-like than cat-like.
"Its huge forearms were equipped with large dew-claws on its thumbs that would have acted like grappling hooks, allowing it to grip and wrestle even bison-sized animals to the ground with relative ease," he said.
From that position, Smilodon used its knife-like teeth for the coup de grace, piercing deeply into the prey's neck.
"Their function was to open deep wounds in vulnerable soft tissue -- most likely the windpipe or major blood vessels of the neck," he said.
Smilodon prowled North America and South America, with many stunning remains of this big cat coming from the famed La Brea Tar Pits in California and elsewhere.
Wroe said its highly refined killing style may have contributed to Smilodon's extinction about 10,000 years ago.
"Although superbly adapted to taking big prey, Smilodon was massively over-engineered for a life subsisting on medium-sized or small animals," he said.
Exactly what reduced the number of big prey is open for debate, but Wroe suspects both climate changes and the arrival of humans played a role.
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