The Repeated Evolutionary Dance of Saber-Toothed Beasts: Nature’s Iconic Comeback


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The skull of a Smilodon, which were made up of saber-toothed cats

The skull of a saber-toothed tiger (Smilodon)

Steve Morton

Carnivores have developed sabre teeth on multiple occasions throughout the history of life— and we now possess a clearer understanding of the reasons these teeth arise as they do.

Sabre teeth possess particular traits: they are extraordinarily elongated, sharpened canines that generally appear somewhat flattened and curved, in place of rounded. Such teeth have independently emerged in varying groups of mammals at least five times, with fossils of sabre-tooth predators discovered in North and South America, Europe, and Asia.

The earliest known appearance of these teeth dates back around 270 million years, within mammal-like reptiles known as gorgonopsids. Another instance is Thylacosmilus, which went extinct approximately 2.5 million years ago and was most closely related to marsupials. Sabre teeth were last observed in Smilodon, commonly referred to as sabre-toothed tigers, which persisted until about 10,000 years ago.

To examine why these teeth continuously re-emerged, Tahlia Pollock at the University of Bristol, UK, along with her associates, analyzed the canines of 95 carnivorous mammal species, featuring 25 that had sabre-toothed characteristics.

Initially, the researchers assessed the forms of the teeth to classify and model them. Following this, they 3D-printed smaller replicas of each tooth in metal and evaluated their efficacy in puncture tests, in which the teeth were mechanically forced into gelatine blocks designed to mimic the density of animal tissue.

This demonstrated that the sabre teeth could penetrate the block with up to 50 percent less force than other teeth, asserts Pollock.

The researchers subsequently analyzed the tooth shape and puncture performance data using a measure called the Pareto rank ratio, which evaluated how optimal the teeth were for strength or puncturing.

“A carnivore’s teeth require sharpness and slenderness to enable the animal to pierce the flesh of their prey; however, they also must be blunt and sturdy enough to avoid breaking during biting,” explains Pollock.

Species like Smilodon exhibited exceptionally long sabre teeth. “These teeth likely emerged repeatedly as they embody an optimal design for puncturing,” states Pollock. “They’re highly efficient at penetration, but that also implies they may be somewhat fragile.” For example, the La Brea Tar Pits in California yield numerous fossils of Smilodon, some possessing damaged teeth.

Other sabre-toothed creatures also featured teeth adeptly shaped for a slightly different function. The cat Dinofelis possessed stockier sabre teeth that equally balanced puncturing and strength, mentions Pollock.

The dentition of additional sabre-toothed species fell between these optimal forms, which may explain why some were not long-lasting. “These features have trade-offs,” explains Pollock. “The attributes of shape that enhance a tooth’s effectiveness for one function detract from performance in another aspect.”

A prevalent theory regarding the extinction of sabre-tooth species is that changing ecosystems and the large prey they presumably hunted, such as mammoths, were vanishing.

The team’s puncture findings lend support to this theory. The enormous teeth might not have been as effective for capturing prey of rabbit size, and the danger of tooth breakage could have increased, leading to the sabre-toothed animals being outmatched by predators more adept at hunting such prey, like cats with smaller teeth, according to Pollock.

“Once the ecological or environmental conditions shift, the highly specialized sabre-tooth predators could not adapt swiftly enough and faced extinction,” remarks Stephan Lautenschlager at the University of Birmingham, UK.

“I believe this contributes to the reason why the sabre-tooth morphology has not reappeared in the contemporary era— we lack megafauna,” suggests Julie Meachen at Des Moines University in Iowa. “The prey simply isn’t available.”

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