Saber-Toothed Cats Likely Pinned Prey With Exceptionally Strong Forelimbs

Posted on July 9, 2010

Saber-toothed cats (Smilodon fatalis) are best known for their huge canines, but a new study found the predators also had exceptionally strong forelimbs for pinning prey. Smilodon fatalis roamed North and South America until 10,000 years ago, preying on large mammals such as bison, camels, mastodons and mammoths.

A new study, reported in the journal PLoS ONE, found clues from bones and teeth that suggest Smilodon relied on their forelimbs as well as their fangs to catch and kill their prey. If a 500 pound saber-toothed cat were alive today and in pursuit of you, it might first pin you to the ground with its powerful forearms, before biting into you with its enormous canines.

Study author Julie Meachen-Samuels, a paleontologist at the National Evolutionary Synthesis Center in Durham, NC., says the size and shape of sabertooth canines made them more vulnerable to fracture than cats living today. She thinks Saber-toothed cats may have used their muscular arms to immobilize prey and protect their teeth from fracture.

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, as well as the extinct American lion, the largest conical-toothed cat that ever lived.

The researchers used the cross-sectional measurements to estimate bone strength and rigidity for each species. When they plotted rigidity against length for the 30 species in their study, species with longer limbs generally had stronger bones. But the data for the saber-toothed cat fell well outside the normal range -- while their leg bones scaled to size, their arm bones were exceptionally thick for their length. 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. Prominent muscle attachment scars on sabertooth limb bones also suggest the cat was powerfully built.

These X-ray images show cross-sectional dimensions of the upper arm bone of a jaguar (A and B) compared to a saber-toothed cat (C and D).

ANIMALS