Why one should never arm-wrestle a saber-toothed tiger

Researchers have found why saber-toothed tigers were a force to reckon with when it came to arm wrestling.

 

A new study has revealed that saber-toothed cats—best known for their supersized canines— also had exceptionally strong forelimbs for pinning prey before delivering the fatal bite.

 

Commonly called the "saber-toothed tiger," the extinct cat Smilodon fatalis roamed North and South America until 10,000 years ago, preying on large mammals such as bison, camels, mastodons and mammoths.

 

Telltale clues from bones and teeth suggest they relied on their forelimbs as well as their fangs to catch and kill their prey.

 

The size and shape of sabertooth canines made them more vulnerable to fracture than cats living today, said author Julie Meachen-Samuels, a palaeontologist at the National Evolutionary Synthesis Center in Durham, NC.

 

"Cats living today have canines that are round in cross-section, so they can withstand forces in all directions. If the prey is struggling it doesn't matter which way it's pulling — their teeth are unlikely to break," she explained.

 

On the other hand, the elongated canines of saber-toothed cats were oval in cross-section, which made them more vulnerable to breaking than their conical-toothed cousins.

 

"Many scientists infer that saber-toothed cats killed prey differently from other cats because their teeth were thinner side-to-side," said Meachen-Samuels.

 

Despite their vulnerable canines, prominent muscle attachment scars on sabertooth limb bones suggest the cat was powerfully built.

 

Saber-toothed cats may have used their muscular arms to immobilize prey and protect their teeth from fracture, she explained.

 

To estimate how strong sabertooth forelimbs were relative to other cats, the researchers used x-rays to measure the cross-sectional dimensions of the upper arm and leg bones of fossils recovered from the La Brea Tar Pits in Los Angeles.

 

They also measured the limb bones of 28 cat species living today — ranging in size from the 6-pound margay to the 600-pound tiger — as well as the extinct American lion, the largest conical-toothed cat that ever lived.

 

The researchers used their cross-sectional measurements to estimate bone strength and rigidity for each species.

 

It was found that sabertooth arm bones were not only larger in diameter than other cats, they also had thicker cortical bone, the dense outer layer that makes bones strong and stiff.

 

"As muscles pull on bones, bones respond by getting stronger. Because saber-toothed cats had thicker arm bones we think they must have used their forelimbs more than other cats did," said Meachen-Samuels.

 

"The findings give us new information about how strong their forelimbs were and how they were built. This is the first study to look inside sabertooth arm bones to see exactly how much stress and strain they could handle," she added. "

 

The findings have been published in PLoS ONE.