The Enigma of the Sabertooth: Was Their Communication a Roar or a Purr?

A study recently delved into the analysis of hyoid bones within the throat to ascertain whether sabertooth tigers were known to roar or purr. Contrary to the conventional understanding that connects the quantity of bones to the type of sound produced, this study hints that the size and shape of the bones might reveal whether the creature purred, roared, or possibly utilized an altogether different method of vocalization. Above is a depiction of Smilodon fatalis. Credit goes to Adam Hartstone-Rose.

A small series of bones might hold the key to this question.

What would a sabertooth tiger sound like when it called out—a commanding roar or a resonant purr? Fresh insights from North Carolina State University explored both possibilities, uncovering that the answer may be more intricate than previously suspected and could hinge on a few specific bones’ structure.

In our present day, felines are primarily divided into two major classes: the pantherine “large cats,” including roaring species such as lions, tigers, and jaguars; and the Felinae “small cats,” comprising purring varieties like lynxes, cougars, ocelots, and domesticated cats.

“On an evolutionary scale, sabertooths branched from the feline family tree prior to these other contemporary groups,” notes Adam Hartstone-Rose, a professor of biological sciences at NC State and the main author of the research. This implies that housecats are more related to lions than they are to sabertooths.

The crucial factor in the debate about the type of sound a sabertooth tiger might have made lies in the study of several minuscule bones found in the throat, according to Hartstone-Rose. The dimensions, form, and number of these bones differ between modern cats that roar and those that purr.

Although vocalizations emanate from the larynx and soft tissues in the throat and not the bones, anatomists observed that the bones anchoring those tissues—the hyoid bones—varied in size and quantity between roaring and purring cats.

Ashley Deutsch, a Ph.D. student at NC State and the primary author of the study, explains, “While a single hyoid bone is found in humans, purring cats possess a linked chain of nine bones, and roaring cats have seven. The absent bones are situated towards the hyoid structure’s top near where it joins with the skull.”

Some have argued that sabertooth tigers must have roared since they have only seven bones in their hyoid structure, Hartstone-Rose says. “But our examination of modern cats’ anatomy revealed that there is no concrete evidence to back this notion since the bones themselves don’t create the sound. The relationship between the number of bones and the noise made has never truly been established.”

The team investigated the hyoid structures of four species of roaring cats: lions, tigers, leopards, and jaguars, and five species of purring cats: cougars, cheetahs, caracals, servals, and ocelots. These were compared to 105 hyoid bones from the legendary sabertooth tiger Smilodon fatalis.

“Though you could claim that the sabertooths roared since they have seven bones, that doesn’t capture the entire picture,” states Hartstone-Rose. “The anatomy is peculiar. They lack extra bones that purring cats possess, but the hyoid bones’ form and size are unique. Some even resemble those of purring cats but are considerably larger.”

The researchers concluded that if the missing bones (referred to as epihyoid bones) were crucial for varying vocalizations, the bones connected to them should appear dissimilar between the two categories. However, the bones appeared nearly identical in shape, whether they were from purring or roaring cats.

Interestingly, the scientists observed more variations in the bones closer to the vocal mechanism; specifically, the thyrohyoid and basihyoid bones. The similarity of the upper bones between both groups implies that if the hyoid structure influences vocalization, the lower bones hold more significance than the upper ones. Therefore, having these essential hyoid bones shaped like those of purring cats might suggest they purred instead of roared.

“We realized that despite historical notions concerning the number of bones in the hyoid structure, no one has confirmed the importance of this difference,” adds Hartstone-Rose. “If vocalization hinges on the number of bones in the hyoid structure, sabertooths roared. If it’s about shape, they might have purred. Since sabertooths share features with both groups, they could have produced an entirely different sound.”

Deutsch surmises, “It’s perhaps more plausible that the hyoids’ size plays a part in vocalization’s pitch. Though Smilodon was not quite as massive as the biggest modern cats, its hyoid bones are significantly larger than those of any living relatives, suggesting they might have had even deeper sounds than the largest tigers and lions.”

Reference: “The roar of Rancho La Brea? Comparative anatomy of modern and fossil felid hyoid bones” by Ashley R. Deutsch, R. Brian Langerhans, Deanna Flores, and Adam Hartstone-Rose, 20 August 2023, Journal of Morphology.
DOI: 10.1002/jmor.21627

This research has been published in the Journal of Morphology and has received support from NC State’s Office of Undergraduate Research. Brian Langerhans, associate professor of biology at NC State, and former NC State undergraduate Deanna Flores also made significant contributions to the project.

Frequently Asked Questions (FAQs) about sabertooth tigers

More about sabertooth tigers

• The roar of Rancho La Brea? Comparative anatomy of modern and fossil felid hyoid bones, Journal of Morphology
• North Carolina State University’s Office of Undergraduate Research