Why Some Saber-Toothed Cats May Not Have Been as Menacing as Previously Imagined

New research suggests that at least one species kept its dagger-shaped teeth inside, not outside, its closed mouth

Saber-tooth cat
At least one species of saber-tooth cat likely kept its long canines inside its mouth, not outside, suggests new research. Pixabay

Saber-toothed cats are often depicted with their long, sharp canines protruding menacingly from beneath their upper lip, even when their mouths are closed. But new research suggests that some of these big cats likely concealed their dagger-shaped weapons inside their mouths until they were ready to strike.

In a study published in the journal Quaternary Science Reviews in April, researchers made the case for why they believe at least one species of saber-toothed cat—Homotherium latidens—mostly kept his big teeth inside, not outside, his mouth.

Mauricio Antón, a paleontological artist and illustrator (or “paleoartist”) and one of the study’s co-authors, long believed that Homotheriums’ large canines protruded when their mouths were completely closed. But in 2016, while watching a video of a modern-day male lion yawning, he had a “Eureka moment,” he tells the New York Times’ Anthony Ham.

“The lower lip was contracting as the mouth was closing, and before full closure, it was enveloping the tip of the canine,” he tells the New York Times.

Illustration of saber-tooth cat
The researchers observed live big cats, reviewed fossil dissections and made a 3-D scan of a Homotherium fossil. Mauricio Antón / Quaternary Science Reviews

This startling realization prompted Antón to reconsider his and other experts' long-held beliefs about the cats’ mouths. Scientists reached their earlier conclusions about saber-toothed cats’ teeth primarily by studying fossils and dissecting modern big cats, which have relaxed lip muscles in death.

Now, though, Antón and fellow collaborators wanted to take a new approach. With fresh eyes, they observed live big cats, reviewed fossil dissections again and made a 3-D scan of a Homotherium fossil. These methods suggested that there simply wasn’t room for the cat’s lower lip to fit between his upper canines and gums, however, there was space for the two upper canine teeth to nestle inside the lower lip.

Homotheriums lived during the Pliocene and Pleistocene epochs some 5.3 million to 11,700 years ago. They had a wide range, spanning from the southernmost tip of Africa to Eurasia and South America, before going extinct roughly 10,000 years ago. Researchers previously believed the cats went extinct 300,000 years ago, but as Smithsonian’s Brigit Katz reported in 2017, the species likely persisted much longer than that and may even have coexisted with modern humans.

The animals used their sharp, three-inch-long canines as “precision weapons,” Antón told the New York Times, slashing the arteries of their prey’s necks and causing them to bleed out and die quickly. Scientists believe Homotherium preyed on baby mammoths, bison and horses, often bringing their carcasses back to their dens for eating.
 
Photos of modern big cats
Researchers studied the mouths of modern big cats to reach their conclusion about extinct Homotherium cats. Mauricio Antón / Quaternary Science Reviews

The researchers also studied cats in the Smilodon family, which had much larger 6-inch-long upper canines, and determined that, unlike Homotheriums, their teeth likely did not fit within their closed mouths. Still, they’re curious to know how the new findings apply to other species of saber-tooth cats.

“This new vision completely changes our image of the life appearance of the saber-toothed felids,” the researchers write in the paper.