The Story of Saberteeth
Nothing had a smile like Smilodon. This fearsome Ice Age cat, the size of a modern-day tiger, had a pair of fangs nearly 18 centimeters long. And you know what?Those giant teeth just might make a comeback. As famous as Smilodon is, it was only thelast and largest of the great sabertooths. Ridiculously long canines had already beena trend for millions of years by the timeSmilodon was prowling around, and scientistshave only just begun to understand how sabertoothedcarnivores used their dental weapons. First things first, though – what does sabertooth actually mean?Technically speaking, a sabertooth is simply any animal with extremely elongated canine teeth. That’s it!And there have been all kinds of sabertoothedcritters over the past quarter-billion years. The very first one we know of is Tiarajudens, a goofy-looking protomammalfrom Brazil that dates back to the PermianPeriod, about 265 million years ago. And over the eons, saberteeth have also shownup in herbivores like the strange, hornedUintatherium, primates like lemurs and baboons, and about 4 millionyears ago in the Pacific Northwest, therewas even a species of sabertooth salmon. But when we say “sabertooth”, usuallywe’re talking about the mammals who usedtheir teeth not just to show off, but to sliceand dice their prey. And for that, we need to get acquainted withsome rather pointy beasts. Let’s rewind back to the Eocene, about 45million years ago. Between then and now, there were basicallythree different kinds of terrifying, cat-likepredators, each of which had evolved theirown saberteeth. The first were nimravids. They looked a lot like cats, but they actually belonged on a totally different branch ofthe carnivore family tree. And they were prickly customers. Fossils show that these carnivores fought a lot, often biting each other on the faceand around the eyes. Now, fast forward to the Miocene Epoch, about20 million years ago and you’ll find barbourofelidsanother group of not-quite-catsMany of them, like Barbourofelis in NorthAmerica, had long pockets in their jaws thattheir teeth could slot into when they closedtheir mouths. Then came the true sabercats. In the Pliocene Epoch there was the leggy,sprinting Homotherium, and more recently,in the Pleistocene, we find the famous Smilodon. So from their own, separate starting points,the nimravids, the barbourofelids, and thetrue cats each wound up with its own typeof sabertooth species. This is a great example of convergent evolution,when different organisms develop the sametrait independently of each other, because that’s just what worksThe marine reptiles known as ichthyosaurs, for example, look a lot like sharks becausethat streamlined shape is just great forslicing through water. And the same goes for flight — both batsand pterosaurs developed wings made of leatheryskin stretched out on long fingers. But when it comes to saberteeth, the questionis… why?What made these teeth so … cutting edge?Well, there’s been no shortage of theoriesabout how sabertooths used their fangs. One of the earliest ideas was that cats usedthem to penetrate the armor of Ice Age animalslike giant armadillos and ground sloths. It’s like they were cats who were also theirown can openers!Other experts thought they used their fangsto stab, jumping on the back of a mammoth,say, and slamming their teeth into their prey. There was even a suggestion that these catswere bloodsuckers!One expert looked at the palate of Smilodonand thought its mouth may have been suitedfor drinking blood. None of these ideas held up, though — mostlybecause saber-shaped teeth were, in fact,incredibly fragile. They were long, flat, and not very good attwisting or bending, as you can see in themany painful-looking broken sabers that havebeen found in the fossil record. So the latest thinking is that, because theirteeth were so fragile, sabercats were probablyvery picky eaters, and they had to time theirbites very carefully. This means that they didn’t hunt like thecats we know today. Lions and tigers don’t slash or rip at theirprey. Instead they rely on what’s called a throttlingbite, which keeps the victim’s mouth orwindpipe closed until it suffocates. Sabercats couldn’t use a throttling bite. So, paleontologists think these cats usedtheir powerful arms to grapple their preyto the ground, and then unleashed a devastatingshear bite to cut through the windpipe andblood vessels of the neck, or maybe open thebelly of their prey. If the initial bite didn’t kill it, theprey would soon die of blood loss. So, Smilodon probably hunted less like yourhouse cat, and more like a great white shark,ambushing its prey in a powerful strike tocause massive damage. Now, this might seem like a high-risk wayto hunt, but it obviously worked!Because, like we’ve already seen, saberteethare one of evolution’s greatest hits. But if they’re so great, what happened tothem?Well, paleontologists think that hunting insuch a specialized way required large prey,like the camels and horses that used to becommon in North America. And when many of the megafauna died off atthe end of the last Ice Age, the sabercatsmight have run out of food to eat. But no one really knows. The fact remains, by the time the last ofthe sabercats disappeared — only about 8,000years ago — there had been some kind ofsabertoothed predator on the planet somewherefor 40 million years!So it only makes sense to consider the possibilitythat evolution will converge yet again onthis winning design. After all, if natural history has shown usanything it’s that good body plans tendto show up over and over. Today, there are over 40 species of cat, largeand small, on the planet. So, given a few million years and the rightevolutionary nudge, we might still see a smilelike Smilodon’s again. What do you want to know about the storyof life on Earth?Let us know by leaving a question in the commentsbelow. And don’t forget to go to youtube. com/eonsand subscribe!Also do yourself a favor and check out someof our sister channels from PBS Digital Studios. Your brain will thank you!