Fangs for show?: making sense of Megantereon’s toothy grimace
For more than a century paleontologists have been puzzling about the function of the sabertooths’ namesake upper canines, with new studies and analyses being published every year, and a sort of consensus is emerging about the way these extinct predators would use their impressive weaponry, as discussed elsewhere in this blog. But a few decades ago it was fashionable to say that such enormous canines could not be used for killing prey and were there only for display. According to that view, sabertooths would intimidate other predators with their showy fangs at kill sites and gain access to carrion, (their primary food source, according to such theories) as well as using them to resolve disputes with rival males for the access to females.
There are many reasons why this theory is wrong, as I discuss at lenght in my book, “Sabertooth”. But the important thing I would like to stress now is that, although the primary function of the “sabers” was related to hunting, it doesn´t mean they weren´t used in display. For instance, let us look at Megantereon. When the animal was relaxed, the tips of the upper canines would protrude beyond the upper lips, an impressive but not neccesarily scary sight.
But when several muscles of the face contracted, pulling back the lips and moving up the nerve pads of the whiskers, the resulting display of teeth would give pause to any rival. However, the facial language of the sabertooths, like that of any cat, would be more complex and subtle than just an option between baring the teeth or not. Felids share with us primates the privilege of having more facial muscles than any other mammal, and they can convey a wide range of emotions to a conspecific with their facial expressions. Baring the teeth more or less fully, opening or closing the eyes (and pupiles), turning the ears one way or the other, all these elements combine to send totally different messages. For instance, in the illustration shown here Megantereon is not really trying to intimidate anyone; instead, it has just caught the smell of another cat in the plants around it, and is performing the “Flehmen”, a non-aggressive gesture that is produced as the animal tries to smell particles in the air with the Jacobson’s organ, located in its palate.
Facial expression is completed with motion. It can be sometimes difficult to read the difference between a Flehmen gesture and an aggresive snarl in a still photograph, but in the live animal there would be no possible confussion. When doing “flehmen”, the cat moves its head slowly to the sides as it tries to capture the scents in the air, but I don’t need to remind any cat owner of what kind of motions and gestures accompany the baring of the teeth in an irritated feline!
But let us not deceive ourselves, even when the teeth are used “for show” in aggresive displays, the animal must be ready to turn threats into real aggression. And that was a definitive weakness of the “display only” theory of sabertooth canine function. If paleontologists rule out the use of the sabers in hunting because of their supposed fragility, then it makes little sense to hypothesize that they were used to scare rivals away, because no display of strength can be used indefinitely without an occasional demonstration. And biting your rivals during a fight is no less dangerous for fragile teeth than it is to bite your prey. In fact, during a dirty fight with a rival cat there is even less control and more chance for breakage.
Sabers were there for show, most certainly. But not merely!