RALEIGH, N.C. — The age-old question of whether the sabertooth tiger roared like a lion or purred like a domestic cat may have been brought a step closer to an answer. A recent study by a team at North Carolina State University suggests that the answer may lie in a few small bones in the cat’s throat and that it’s more intricate than previously believed.
Modern feline species are categorized into two main groups: the pantherine “big cats” which comprise roaring creatures like lions, tigers, and jaguars, and Felinae “little cats” like cougars, lynxes, and our common housecats which purr.
“Evolutionarily speaking, sabertooths split off the cat family tree before these other modern groups did,” says study corresponding author Adam Hartstone-Rose, a professor of biological sciences at NC State, in a university release. “This means that lions are more closely related to housecats than either are to sabertooths. That’s important because the debate over the kind of vocalization a sabertooth tiger would have made relies upon analyzing the anatomy of a handful of tiny bones located in the throat. And the size, shape and number of those bones differ between modern roaring and purring cats.”
While human anatomy includes one hyoid bone, cats that purr have nine, intricately linked in a chain, and those that roar possess only seven.
“While humans have only one hyoid bone, purring cats have nine bones linked together in a chain and roaring cats have seven,” says study lead author Ashley Deutsch, a Ph.D. student at NC State. “The missing bones are located toward the top of the hyoid structure near where it connects to the skull.”
A prevalent assumption was that since sabertooth tigers only have seven bones in this structure, they must’ve roared.
“But when we looked at the anatomy of modern cats, we realized that there isn’t really hard evidence to support this idea, since the bones themselves aren’t responsible for the vocalization,” says Hartstone-Rose. “That relationship between the number of bones and the sound produced hasn’t ever really been proven.”
Researchers delved into this mystery by examining the hyoid structures of various roaring and purring cats, comparing them to the iconic sabertooth tiger, Smilodon fatalis. What they found challenges conventional wisdom.
“You can argue that since the sabertooths only have seven bones they roared, but that’s not the whole story,” notes Hartstone-Rose. “The anatomy is weird. They’re missing extra bones that purring cats have, but the shape and size of the hyoid bones are distinct. Some of them are shaped more like those of purring cats, but much bigger.”
If certain missing bones (epihyoid bones) were central to different vocalizations, the bones connected to them should show variation between purring and roaring cats. Surprisingly, those bones seemed nearly identical in both groups. This suggests that if these bones play a part in vocalization, it’s likely the ones closer to the vocal apparatus, rather than the upper ones, that matter most.
This discovery implies that sabertooths could have potentially purred, given the shape of these crucial hyoid bones.
“We found that despite what history has told us about the number of bones in the hyoid structure, no one has validated the significance of that difference,” says Hartstone-Rose. “If vocalization is about the number of bones in the hyoid structure, then sabertooths roared. If it’s about shape, they might have purred. Due to the fact that the sabertooths have things in common with both groups, there could even be a completely different vocalization.”
“It is perhaps most likely that the size of the hyoids plays a role in the pitch of vocalization. Although Smilodon wasn’t quite as big as the largest modern cats, its hyoid bones are substantially larger than those of any of their living relatives, so potentially they had even deeper vocalizations than the largest tigers and lions,” Deutsch adds.
The study is published in the Journal of Morphology.
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