Skull of a saber-toothed tiger (Smilodon)
Steve Morton
Predators have evolved saber teeth many times throughout history the life – and now we have a better understanding of why these teeth develop the way they do.
Saber teeth have very specific characteristics: they are long, pointed canines that tend to be slightly flattened and curved rather than rounded. Such teeth have evolved independently at least five times in different groups of mammals, and saber-tooth fossils. predators They have been found in North and South America, Europe and Asia.
Teeth are known to have appeared 270 million years ago, in mammal-like reptiles called gorgonopsids. It is another example Thylacosmiluswhich disappeared about 2.5 million years ago and was most closely related to marsupials. Saber teeth were last seen SmilodonThey are often called saber-toothed tigers, which existed until about 10,000 years ago.
Those teeth continued to evolve again to research, Tahlia Pollock At the University of Bristol (UK) and colleagues looked at the dogs of 95 species of carnivorous mammals, including 25 saber-toothed ones.
First, the researchers measured the shapes of the teeth to classify and model them. They then 3D printed smaller versions of each tooth in metal and tested their performance in drill tests, where the teeth were mechanically pushed into blocks of gelatin designed to mimic the density of animal tissue.
This showed that the saber teeth were able to pierce the block with 50 percent less force than the other teeth, Pollock says.
The researchers then evaluated the tooth shape and drilling performance data using a measure called the Pareto rank ratio, which judged how well teeth were better at strengthening or drilling.
“A carnivore’s teeth must be sharp enough and slender enough for the animal to pierce the flesh of its prey, but they must also be strong enough so that the animal does not break while biting,” says Pollock.
Like animals Smilodon he had very long saber teeth. “These teeth were probably resurfacing again and again because they represent the perfect drilling design,” says Pollock. “They’re really good at digging, but that also means they’re a little fragile.” For example, the La Brea Tar Pits in California contain many fossils Smilodonwith some broken teeth.
Other saber-toothed animals also had teeth that were ideally shaped for a slightly different job. the cat Dinofelis According to Pollock, it had saber teeth that more evenly balanced punch and strength.
Other saber tooth teeth the species They sat in between these optimal forms, which is why some of them didn’t last long. “These kinds of things get traded,” says Pollock. “The aspects of shape that make a tooth good at one thing make it bad at another.”
One of the main hypotheses for the extinction of the saber-tooth species is that ecosystems were changing and their giant prey, such as mammoths, were disappearing.
The team’s drilling findings confirm this. Huge teeth would have been less effective at catching prey the size of a rabbit, and the risk of tooth breakage increased, so saber-toothed animals would have been outmatched by more efficient predators. Hunting such prey, like cats with smaller teeth, says Pollock.
“As soon as ecological or environmental conditions changed, highly specialized saber-tooth predators could not adapt quickly enough and became extinct,” he says. Stephan Lautenschlager at the University of Birmingham, UK.
“I think that’s part of the reason we haven’t re-evolved this saber-tooth morphology today: we don’t have megafauna,” he says. By Julie Meach at Des Moines University in Iowa. “There is no booty.”
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