How saber-toothed cats grew their mouth swords

How much time does it take to grow a 7-inch-long mouth dagger? Our new video explains:

The saber-toothed cat Smilodon fatalis roamed America during the Pleistocene before going extinct about 10,000 years ago. A top predator, Smilodon seemed to use its sabers to slit the throats of its prey (terrifying!). A new paper published in the journal PLoS ONE investigates how the sabers developed — and found the sabers grew almost twice as fast as modern lion canines.

Jack Tseng, co-author on the paper and a paleontologist at the American Museum of Natural History, is fascinated by the these prehistoric killing machines. "A lot of us think they're evolutionary show-offs because the sabers are such an extreme adaptation," Tseng says.

Tseng and his colleagues including Robert Feranec reviewed fossils from the La Brea Tar Pits in Los Angeles. By analyzing the chemical composition and structure of the sabers, the researchers learned the extinct cat's sabers grew at a speedy 6 mm per month, almost twice as fast as human fingernails. Knowing the growth rates and timing of development is important, Tseng says, because they provide clues about the lifestyles of these extinct animals.

For example, even though the sabers grew relatively quickly, the researchers also found that they weren't fully developed until the cats were at least 3-years-old. Tseng says this might mean saber-toothed cubs were reliant on their parents for longer than modern big cats, whose canines often finish growing in a few years. Tseng says: "We're still finding out new things about these animals even though they've been known for over 100 years."

Watch the video above to learn more. This video was made possible by the Alfred P. Sloan Foundation. Never want to miss a new Vox Video? Subscribe.