Why Saber Teeth Are Extinct

“Saber teeth”, as we have mentioned, is a term that is used generically to refer to several species of mammals characterized by the presence of large canines that protrude on both sides of the mouth and that lived at different times during the Cenozoic.

Despite their name, they are not related to the tigers that we know today, but they were compared to them due to their large size (somewhat smaller than lions). Saber teeth belong to the Machairodontinae subfamily , while present-day tigers and lions belong to the Felinae subfamily, both from the Felidae family. Macairodontins and felines have a common origin in the Upper Oligocene (23 million years ago), a period in which the first known feline lived: Proailurus.

This subfamily includes several extinct genera, and among them the popular Smilodon stands out . They owe their name “saber teeth” to the long, curved shape, similar to that of sabers, of their fangs ; homologous to those possessed by the rest of the felids. Smilodon was characterized by being the genus with the largest canines, reaching up to 20-26 centimeters, both in males and females, in the case of the Smilodon populator species . Other famous species are S. fatalis or S. gracilis .

Thanks to the fossil record, it was determined that saber teeth inhabited the entire American continent . In addition, it was estimated that they measured between 1-1.1 meters in height and that a specimen could reach 300 kilograms.

Felines kill their prey by suffocation, biting them in the throat or snout to prevent the passage of air to the lungs and, only when the prey are small, does the bite occur on the head or neck to break the bones of the skull or vertebrae in the cervical area.

However, saber tooth fangs were susceptible to breaking if used to bite into bone tissue, which is why they specialized in large prey (small prey carried a greater risk of striking their bones and causing the rupture of fangs). It is strange to think that despite the large size of these structures, they made the saber tooth bite less powerful. Surprisingly, the efficiency lay in the angle they could reach when opening the jaw, reaching up to 120º of opening (the current lion reaches 65º).

Unlike the felines, the macairodontins did not seek to kill their prey by suffocation (which would suppose a great energy expenditure due to the need to immobilize the prey and maintain the bite until it died asphyxiated). The most widespread theory of the utility of these large fangs in saber teeth was hunting large prey from below to trap the throat and sever it. Sharp, curved fangs penetrated the victim neutralizing it much faster than by suffocation. Some specimens even had the edges of the serrated tusks so that the cut produced a faster and cleaner incision, reducing the energy cost that occurred during hunting and the possible risks posed by the prey (kicks, horns). This highlights the role of the canines, that of tearing, a function that is increased when the prey is held and immobilized on the ground. On the other hand, it is believed that in addition to blocking their respiratory flow, these canines also cut the main blood vessels that carry blood to the brain, causing the prey to even lose consciousness before dying, ceasing to pose a threat.

In the event that the prey escaped before being immobilized, it would quickly bleed out from the bite. As a consequence it dies and the saber tooth is able to recover it later.

In comparison to felines current saber teeth had other features such as:

• They were not great runners because of their stout build and the length of their tail, only 35 centimeters long, which in existing cats is long and serves to maintain balance during the race.
• They had a much more developed sense of smell.
• They had a small brain.
• His limbs were very muscular and powerful.
• Retractable paws, a quality they share with cats, but not with tigers and lions.
• They lived in packs. It is thought that they cared for members who were injured or sick.

The genus Smilodon silenced its roar at the end of the Pleistocene, the last ice age of the Quaternary, that is, the saber teeth were extinct 12,000-10,000 years ago .

Drastic environmental and climatic changes occurred that could generate a cascade of consequences in the food chain of saber teeth. One of these consequences was that the distribution of large prey became much more errant (in 5,000 years there was an increase in temperature of more than 6º, which could have a negative influence on this distribution), making it difficult to hunt the teeth. saber.

These climatic changes caused the retreat of the glaciers, as well as the change of the seasons and the increase in rainfall, which influenced and altered the local ecosystems. However, Smilodon had survived other glacial periods before, so there must have been an added factor that differentiated it from previous climatic events, such as changes in temperature and vegetation . The latter changed in a way that made it more difficult for felids to stalk their prey and coexist with other predators. Thus, the competition between various species of carnivores was very violent.

To all this was added the arrival of the first hominids to the American continent , where saber teeth were distributed. Humans were able to contribute to its extinction by hunting large mammals (such as mammoths, mastodons, moose, or bison) that were common prey for saber-toothed teeth.

Finally, during the most abrupt climatic changes at the end of the Quaternary, ecosystems were not capable of harboring and maintaining all the diversity of large predators, so the less specialized and flexible species increased their chances of survival. It was then that the cats had an advantage and finally, they succeeded the macayrodontines.

Based on the previous section, we can say that the extinction of the saber teeth could have occurred, broadly speaking, due to the scarcity of prey due to climate changes and competition with other predators. Scientists at Vanderbilt University have developed research that can help clarify this fact ¹ .

The study in question analyzes fossilized remains through a technique called “micro wear analysis of tooth texture” (developed by study co-author Peter Ungar of the University of Arkansas). The director of the study, Larisa DeSantis, shares that in situations where food is scarce, today’s felines consume a greater part of the carcass of the prey, including its bones. When this happens, the teeth have large and deep grooves, as opposed to those that have chewed only meat, which show small marks in parallel.

The analysis revealed that the saber teeth exhibited wear patterns similar to those of today’s African lion , which chews on some bones when it eats. Despite all this, they found no evidence as to whether they used corpses to a greater extent throughout the period in which they existed, but the analysis suggested that the proportion of corpses they consumed decreased towards the end of their existence.

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