The Story of Saberteeth

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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 the
last and largest of the great sabertooths. Ridiculously long canines had already been
a trend for millions of years by the timeSmilodon was prowling around, and scientists
have 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 sabertoothed
critters 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 Permian
Period, about 265 million years ago. And over the eons, saberteeth have also shown
up in herbivores like the strange, hornedUintatherium, primates like lemurs and baboons, and about 4 millionyears ago in the Pacific Northwest, there
was even a species of sabertooth salmon. But when we say “sabertooth”, usually
we’re talking about the mammals who usedtheir teeth not just to show off, but to slice
and dice their prey. And for that, we need to get acquainted with
some rather pointy beasts. Let’s rewind back to the Eocene, about 45
million years ago. Between then and now, there were basically
three different kinds of terrifying, cat-likepredators, each of which had evolved their
own 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, about
20 million years ago and you’ll find barbourofelidsanother group of not-quite-cats
Many of them, like Barbourofelis in NorthAmerica, had long pockets in their jaws that
their 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 type
of 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 for
slicing through water. And the same goes for flight — both bats
and pterosaurs developed wings made of leatheryskin stretched out on long fingers. But when it comes to saberteeth, the question
is… why?What made these teeth so … cutting edge?Well, there’s been no shortage of theories
about how sabertooths used their fangs. One of the earliest ideas was that cats used
them to penetrate the armor of Ice Age animalslike giant armadillos and ground sloths. It’s like they were cats who were also their
own can openers!Other experts thought they used their fangs
to stab, jumping on the back of a mammoth,say, and slamming their teeth into their prey. There was even a suggestion that these cats
were bloodsuckers!One expert looked at the palate of Smilodon
and thought its mouth may have been suitedfor drinking blood. None of these ideas held up, though — mostly
because saber-shaped teeth were, in fact,incredibly fragile. They were long, flat, and not very good at
twisting or bending, as you can see in themany painful-looking broken sabers that have
been found in the fossil record. So the latest thinking is that, because their
teeth were so fragile, sabercats were probablyvery picky eaters, and they had to time their
bites very carefully. This means that they didn’t hunt like the
cats we know today. Lions and tigers don’t slash or rip at their
prey. Instead they rely on what’s called a throttling
bite, which keeps the victim’s mouth orwindpipe closed until it suffocates. Sabercats couldn’t use a throttling bite. So, paleontologists think these cats used
their powerful arms to grapple their preyto the ground, and then unleashed a devastating
shear bite to cut through the windpipe andblood vessels of the neck, or maybe open the
belly of their prey. If the initial bite didn’t kill it, the
prey would soon die of blood loss. So, Smilodon probably hunted less like your
house cat, and more like a great white shark,ambushing its prey in a powerful strike to
cause massive damage. Now, this might seem like a high-risk way
to hunt, but it obviously worked!Because, like we’ve already seen, saberteeth
are one of evolution’s greatest hits. But if they’re so great, what happened to
them?Well, paleontologists think that hunting in
such a specialized way required large prey,like the camels and horses that used to be
common in North America. And when many of the megafauna died off at
the 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 of
the sabercats disappeared — only about 8,000years ago — there had been some kind of
sabertoothed predator on the planet somewherefor 40 million years!So it only makes sense to consider the possibility
that evolution will converge yet again onthis winning design. After all, if natural history has shown us
anything it’s that good body plans tendto show up over and over. Today, there are over 40 species of cat, large
and small, on the planet. So, given a few million years and the right
evolutionary nudge, we might still see a smilelike Smilodon’s again. What do you want to know about the story
of life on Earth?Let us know by leaving a question in the comments
below. And don’t forget to go to youtube. com/eons
and subscribe!Also do yourself a favor and check out some
of our sister channels from PBS Digital Studios. Your brain will thank you!

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