Sabre-toothed cats’ teeth were hidden – 05/08/2022 – Science

Close your eyes and imagine being face to face with a saber-toothed cat. Most likely you’ll see in your mind’s eye the long, curved upper canines—particularly sinister because those dagger-shaped teeth were visible even when the cat closed its mouth.

What appears in your imagination may be incorrect, at least for a species of saber-toothed cat that was one of the most widespread in Earth’s ancient history.

In a study published last month in the journal Quaternary Science Reviews, a team of researchers argues that many artistic reconstructions of the homotherium barks are wrong. The depictions of cats with sharp teeth in readiness need to be revised, because the defining characteristic of the animal was a concealed weapon until the cat was ready to pounce or opened its mouth.

THE homotherium barks was “the most powerful Old World Pleistocene saber-toothed cat,” said paleontological artist Mauricio Antón, an expert on saber-toothed cats and one of the study’s authors. According to the fossil record, Homotherium first appeared about 4 million years ago, during the Pliocene.

The species lived from the southern tip of Africa, across Eurasia and as far as South America. A fossil site at Friesenhahn Cave in Texas suggested that groups of saber-toothed animals could hunt collectively to bring down mammoths. The species became extinct 10,000 years ago.

The cat was the size of a lion, weighed up to 250 kilograms, and had long, scimitar-shaped, serrated upper canines. In a paper Antón wrote in 2009, he concluded, “The tips of the Homotherium sabers would have been visible in life, protruding beyond the lips,” even when the cat was at rest. In other words, the Homotherium fit the stereotyped profile of the saber-toothed cat.

More recently, however, Antón has begun to wonder whether he and other paleontological researchers are misunderstanding the cat’s deadly dentition.

For decades, almost everything scientists have known about saber-toothed cats has come from fossils and dissections of modern big cats. “When you dissect a dead big cat, the lips are in a particular position because the muscles that control the lips relax,” Antón said. “That’s where our data came from.”

Then, in 2016, while watching a video he had taken of a magnificent lion yawning in Botswana’s Okavango Delta (Africa), Antón noticed something he had never seen before: “The lower lip was twitching as the mouth closed. and, before full closure, it involved the tip of the canine. I thought, ‘Am I really seeing this?’ It was a eureka moment.”

To understand the implications of their observation, Antón and a team of scientists studied living big cats in minute detail. They analyzed fossil dissections with what Antón described as “new eyes”. And they did a 3D CT scan of an intact 3-million-year-old fossil of a Homotherium latidens which had been excavated in Perrier, France.

Gema Siliceo, a postdoctoral researcher at Comenius University in Slovakia and co-author of the study, said the combination of these techniques provides “an enormous amount of information that we can use to infer what an extinct feline would look like in life.”

Their studies confirmed that there was simply no room for the lower lip and soft tissue to fit between the Homotherium’s upper canine and the gingiva. But there was room for the canines to be hidden against the closed part of the jaw, the lower jaw.

Whatever their aesthetic, saber-toothed cats remained fearsome predators. Unlike modern big cats like lions and tigers, the Homotherium’s narrow, blade-like teeth were “precision weapons,” Antón said. “When the sabers cut the arteries in the neck,” he added, “the prey lost blood very quickly and passed out within seconds.”

A lion’s upper canines are about 3.7 centimeters long. Those from the Homotherium were 7.3 centimeters. The largest saber-toothed cat, the 408-kilogram Smilodon fatalis, could have been 14.7 cm long, which is why the new findings don’t apply to Smilodon’s teeth: no jaw could accommodate such teeth.

Still, the study authors wonder where investigations like this might lead next. “We know about 30 to 40 species of saber-toothed cats,” Siliceo said, “but there are still many more to be found.” Earlier this year, scientists in China described a previously unknown dwarf saber-tooth and another the size of a jaguar.

According to Antón, this could be just the beginning. “We have a whole biosphere in the museum drawers waiting to be discovered,” he said.

Translated by Luiz Roberto M. Gonçalves


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