The Evolution of Cats: 5. Sabertooths, Part 1

A multi-million-year predator niche has been empty for the last 11,000 years.

We should be celebrating that fact. Instead, we have forgotten the terror that these ferocious animals inspired in our ancestors.

We wish they were still around.

Well, it’s understandable. If safety could be guaranteed, who wouldn’t want to go see a live sabertoothed cat at the zoo?

If…

Paleontologists have gotten DNA from well-preserved fossils of the two most famous sabertooths – Smilodon and Homotherium. (Barnett and others)

But if Jurassic Park-style cloning really worked LINK, safety could not be guaranteed in the saber-cat enclosure.

Nobody knows how these extinct animals behaved.

Some of them were probably good jumpers (Morales and others); most could climb; and a few behemoths had the brutal momentum that a half-ton body mass makes possible when they charged. (Antón; Turner and Antón)

Anyway, they were all cats and therefore moody, quick to react, and unpredictable.

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A modern human would be eyeball-to-eyeball with Smilodon populator here.

Yet, despite the risks, we all so want to see a sabertoothed cat!

The idea of a living sabertooth isn’t total fantasy. It’s very unlikely, but a new one really could appear any day.

After all, evolution is still going on.

And for the last fifty million years (Antón), that ambush-and-slash niche for sabertoothed mammals has always been refilled after a brief vacancy. Then it has been occupied for tens of millions of years at a stretch.

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We could all go back to caves . . .


It’s good to be an apex predator.

Cats didn’t invent saberteeth. These killing tools go back to the days before mammals.

How did cats get them and why aren’t there any sabertooths around today?

Saberteeth

All cats are hypercarnivores. That’s why Fluffy the Housecat can’t live on dog food – it needs the special balance of protein and amino acids that canned and dry cat food contains.

In the wild, cats depend on prey animals. To survive, their canine teeth have evolved into fangs. (Holliday and Steppan; Kitchener and others)

Bengal tigers have the largest fangs of any modern cat – up to 4 inches (10 cm) long. (Heske, Lab 19)

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The fangs of this Brazilian jaguar along the Rio Negro are impressive, too.


In comparison, Smilodon’s saberteeth were almost a foot (28 cm) long. (van den Hoek Ostende and others) But those weren’t really fangs.

In today’s big cats, upper fangs are rather cone-shaped – thick at the base and tapering up into a point.

Saberteeth were much flatter, front to back, than the fangs of any “normal” modern cat. (Martin, 1980; van den Hoek Ostende and others)

The edges looked like knives. Indeed, the technical name for sabertoothed cats is Machairodontinae, which means “Knife-Tooths.” (Antón; Turner and others)

But appearances are deceptive. Saberteeth were actually blunter than a steel blade, although sometimes they were serrated. (Turner and Antón)

Mechanical experiments show that saberteeth could only cut through hide and animal tissues when the cat also made a slicing movement during its killing bite. (Wheeler)


Hence the name ambush-and-SLASH for a sabertoothed predator. In contrast, all modern cats use a stalk-and-pounce hunting technique. (Werdelin, 1989)

Paleontologists say that there are subtle differences in saberteeth between two major sabertoothed cat tribes, the Homotheriini and the Smilodontini.

Homotherium and its relatives were scimitar-toothed. Their saberteeth tended to be broad and very flat, with coarse serrations. (Antón; Martin, 1980)

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Homotherium


The Smilodontini were dirk-toothed cats. Their sabers were generally longer and straighter, less flattened, and with very fine serrations to none at all. (Antón; Martin, 1980)

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Smilodon populator was an extreme dirk-tooth.  

Per Antón, the species name “necator” isn’t used any more.

These subtle differences matter a lot to experts. That’s why you’ll often see “dirk-tooth” or “scimitar-tooth” on the Web or in books about sabertoothed cats.

But for general purposes, it’s still perfectly okay to just call them all sabertooths.

Sabertooths down through time


These specialized upper canine teeth aren’t all that unusual in fossil carnivores.

Since the K/T extinction sixty-five million years ago, at least four mammal groups have had them. (Kitchener and others)

All four, plus the very first sabertooths – those Permian gorgonopsids we met last time – are shown here, drawn to scale:

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That must be The Doctor. Only a Time Lord could get into such a predicament – millions of years actually separate some of these animals from the others.
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