Paleontology

"Saber Tooth Tigers" Weren't The Only Saber Teeth Out There

When it comes to prehistoric mammals, there are two that spring immediately to mind: the mammoth or mastodon (we're not going to split that wooly hair quite yet), and the saber-toothed cat (often wrongly called a "saber-tooth tiger"). There's just something really surreal and terrifying about an animal that's bigger than any living cat, with 11-inch incisors jutting out of its mouth. But as it turns out, the fact that we're living in an age without saber-toothed animals is the anomaly. Saber-toothed meat-eaters have evolved no less than seven separate times in the history of the planet — so why aren't there any left? We talked to Bill Simpson, the Head of Geological Collections at The Field Museum in Chicago, to find out.

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Thylacosmilus atrox

Nasty, Big, Pointy Teeth

The best-known saber-toothed animal was the saber-toothed cat, but that might just be because it was probably the only one recent enough to have eaten us. It had some relatives with similar sets of chompers, most notably its four-foot-long (1.2 meters) European cousin Megantereon, but what's really strange is the wealth of animals that didn't have anything to do with that family. Take the Thylacosmilus (discovered, incidentally, by the Field Museum's own Elmer Riggs), for example. It wasn't a cat at all, but a marsupial relative, and it had a bony sheath for its giant incisors. And then there's Machaeroides, the oldest saber-toothed mammal known — it was older than even the concept of a cat.

"[Saber teeth seem] to have been a strategy for going after large-bodied prey," Simpson told Curiosity. "Though there's some controversy about that." He noted that modern big cats such as lions generally kill their prey by crushing the windpipe and suffocating them. It's effective, but it also requires the predator to stay right on top of their prey up until the moment of death — and it's a hard strategy to pull off against an elephant-sized animal. But with a pair of swords for teeth, they could deliver a single killing blow, then wait for their prey to succumb to their wounds.

So if that strategy works so well, then why don't we see it in any modern carnivores? Basically, because the animals that it works well on all died out. "They were adapted to feeding on large prey," Simpson said. "The saber-toothed cat in the New World survived up until the point that the megafauna went extinct. It may have over-specialized, and couldn't compete with the more generalized predators." In other words, when it comes to taking down giants, saber teeth are the way to go. But when the giants are all gone, they just get in the way.

Saber Teeth Across The Ages

Every animal we've mentioned so far lived between about 56 million years ago and 11,000 years ago. But the oldest saber-toothed animals of all date back much further — as far as 250 million years. That's before the dinosaurs themselves.

Gorgonopsians would have looked something like a combination between a komodo dragon and a large dog, blown up to 1,000 pounds and armed with two massive saber teeth. It probably used those teeth the same way all of the others did: to make slashing attacks intended to deal death quickly. But when you place gorgonops in its proper position in the evolutionary tree, a clearer picture emerges of why some animals develop saber teeth and others don't.

See, every other animal in this article is a mammal, but gorgonops is a therapsid — also known as a "mammal-like reptile". These are the prehistoric ancestors of every modern mammal, and one of the ways that they set themselves apart from their ancestors was their teeth. Unlike reptiles, fish, and even dinosaurs, synapsids (the group that includes both mammals and therapsids) have a mouthful of molars, incisors, canines, and other specialized teeth. Without that baseline trait of widely varied teeth, it's unlikely that saber teeth would have ever developed, and then prehistoric cavemen wouldn't have anything to use as a can-opener.

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