The Sabertooths, Part 4: The First Sabertoothed Cats

The early history of the two major saber-cat tribes isn’t well understood yet. (Martin and others, 2011d; Werdelin and others)

Different paleontologists call the first sabertoothed cats by different names. (Antón; van den Hoek Ostende and others; Werdelin and others) The most controversial names are “Miomachairodus,” “Machairodus,” and “Amphimachairodus.”

“This discussion is far from settled, but at the very least shows that these forms grade into one another.”
— Werdelin and others

While professional fossil-cat herders continue to debate the details and slowly reach a consensus, I have chosen two specific sources to follow, even though they aren’t totally consistent:

  • Mauricio Antón calls those early sabertooths Macharoidus and describes Amphimachairodus as a separate group. (Antón)
  • Werdelin and others suggest that “Miomachairodus,” “Machairodus,” and “Amphimachairodus,” whatever their exact relationships to one another were, are the ancestors – somehow – of Homotherium (Werdelin and others), the scimitar-toothed sabercat.

Okay. Let’s move on to the Mediterranean region as it was in 12 Ma (million years ago), when a time traveler might have seen Machairodus there (at a safe distance) and mistaken it for one of today’s big cats.

Machairodus was generally built like a modern tiger, except for a very narrow face, a longer neck than any big cat has today, and a short tail. (Antón; Turner and Antón)

Machairodus also had saberteeth . . . and advanced ones at that. (Antón)

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Experts have painstakingly pieced Machairodus together from fossil fragments found in a natural carnivore trap near Madrid.

Those sabers are impressive, but they look a little strange to paleontologists. Perhaps “out of place” is a better way to put it.

The saberteeth are so advanced, they might have belonged to Homotherium, but Machairodus doesn’t have the rest of a sabertoothed cat’s features, like massive cranial structures to support powerful jaw muscles, powerful forelimbs, and a short hindlegs. (Antón)

In fact, this very feline animal had long back legs that probably made it quite a good jumper. (Antón; Turner and Antón)

So our time traveler didn’t make it back to today because they saw a tiger-sized sabertoothed cat on the other side of a wide crevice and thought they were safe.

For paleontologists, the saberteeth show that the Homotheriini evolved saberteeth first and then worked out the rest of the cranioskeletal adaptations later. Scientists call this process mosaic evolution. LINK (Antón)

Even without other physical characteristics that would enhance the advantages of saberteeth, Machairodus thrived. (Antón)

Its earliest fossils come from Turkey and Africa. After that, these saber-cats spread out across both Eurasia and North America. (van den Hoek Ostende and others)

Machairodus was the first member of the cat family to reach the size of modern lions and tigers, and it didn’t stop there. One of its most successful species, M. aphanistus, was over 3 feet tall (100 cm) at the shoulder. (Antón)

Perhaps being big offset the lack of other sabertooth features.

Saberteeth allowed for a faster kill. (Antón; Turner and others) Machairodus might not have been able yet to tackle the plant-eating giants that thrived back then, its size meant that it could have taken and eaten prey as big as what today’s big cats can handle. (Deng and others)

Quicker.

This was quite an advantage in a highly competitive environment.

Over time, sabertooths became more efficient as they slowly developed all the other physical marks of an advanced sabertooth. (van den Hoek Ostende and others)

They were ready to go, once they had the whole “sabertooth complex.” (Antón)

This included, but wasn’t limited to, powerful forelegs and shoulders to overpower prey and a long, muscular neck to safely position the sabers for that killing bite. (Antón; Turner and others)

There were still a few limits, though.

Megaherbivores as huge as the junior mastodons that Homotherium would eventually tackle in the Pleistocene existed back in the Miocene (Antón; Agustí and Antón; Prothero, 2006), but they were probably safe from all of the early sabertooths. (Antón)

Machairodus followed smaller prey – zebra-sized migrating horses – out of central and western Asia into Europe, where it found lots of other suitable plant-eaters. (Agustí )

This sabertoothed cat coexisted with the barbourofelids (Agustí ; Antón) and held its own against Europe’s big amphicyonid beardogs and ursids (members of the bear family Ursidae). (Hunt, 1989)

Around 10 Ma, a more advanced sabertooth – Amphimachairodus – replaced Machairodus. (Antón)

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That’s an Amphimachairodus skull (bottom) and drawings of the partial skull of Proailurus, the Dawn Cat (top) – the probable ancestor of Pseudaelurus and therefore of both modern cats and sabercats.

Some fifteen million years of evolution separate the two.

A-Mach was even bigger than Machairodus – almost 4 feet high (120 cm) at the shoulder – and its head was longer and narrower. (Turner and Antón)

This saber-cat also had a very muscular neck, as well as enormous dewclaws for holding onto prey animals like horses and antelope. (Antón)

However, A-Mach still overall looked like a modern cat. (Antón; Werdelin and others)

That is, it was still very primitive.

Today we tend to think the sabertooths were primitive because they went extinct. Actually, Homotherium and Smilodon were very advanced specialists. (Antón; Turner and Antón) It’s today’s cats that are the die-hard conservatives.

No cat owner will be surprised by this, of course, but it shows up not only in mood but also in the cat’s build.

Modern felines still have the general Pseudaelurus body plan. They have just changed the legs and feet a bit to make it easier to move on the ground. (Antón; Turner and Antón)

Sabercats were much more specialized, and they still managed to cover a lot of ground.

A “veritable freeway” for both predators and prey existed across the Bering land bridge between Eurasia and North America. (Prothero, 2006, including quote)

In addition, a tectonic collision between Africa and Eurasia had opened up routes between these two continents.

Primitive members of the elephant family, which would eventually evolve into Ice-Age mastodons and mammoths, ventured out of Africa into the wider world while Eurasian sabertooths followed prey into Africa’s mosaic landscapes of forest and wooded grasslands. (Agustí and Antón; Strömberg)

Fossils of these African sabertoothed cats from as far back as 10-11 Ma are still being excavated and studied. (Antón; Peigné and others)

Perhaps the most impressive to date is Machairodus kabir from Chad. This enormous saber-cat might have weighed almost half a metric ton! (Peigné and others)

That’s plenty big enough to take down plant-eaters weighing close to a ton. (Peigné and others)

Another sabertooth, with the jaw-breaking name of Lokotunjailurus, has been found in both Chad and Kenya. The size of a modern lioness, it goes back to about 7 Ma. (Antón; de Bonis and others)

At first, paleontologists thought this long-limbed, graceful sabertoothed cat was Machairodus. However, further study has shown that Lokotunjailurus was a separate species, with some similarities to Homotherium. (Antón; van den Hoek Ostende and others)

It’s too bad there are no common names for these beautiful animals. The scientific names are so long, especially in a family tree!

Some paleontologists (Werdelin and others) draw a very general family tree of the Homotheriini this way: Machairodus around 12 Ma, through Amphimachairodus at about 10 Ma, to Homotherium.

Perhaps Lokotunjailurus fits in there between Amphimachairodus and Homotherium. (van den Hoek Ostende and others)

Finally, according to phylogenetic computer analyses, Homotherium showed up in Europe around 6 Ma and then in North America two or three million years later. (Werdelin and others)

Its earliest fossils go back to 4 Ma – about when the oldest known “Felis” modern-cat ancestor lived in Greece. The sabercat remains were found in both Africa and the Ukraine, which means that Homotherium could have evolved in either Eurasia or Africa. (Antón and others; Werdelin and others)

The roots of Smilodon’s tribe

Many cat fossils are still buried by time, waiting to be discovered. (Johnson and others)

Smilodon’s ancestors are among the missing. (Antón; Werdelin and others) However, some possible early candidates have been recognized. There was Promegantereon, around 11 to 10 Ma. (Werdelin and others)

It was the size of a puma, with saberteeth that weren’t very long but were flat in cross-section, with a curve. (Salesa and others, 2010b)

Promegantereon was smaller than Machairodus, but it had some of the other sabertooth complex features, including powerful forelegs, a big dewclaw, and a narrow head. (Antón; Turner and Antón)

This saber-cat was still primitive, like Machairodus, but already it was built to wrestle down prey (Salesa and others, 2010a) – a trademark of the Smilodontini hunting style.

Even early on, strength mattered in this group.

Promegantereon hunted deer, antelope (Turner and Antón), and other prey in Eurasia and Africa from about 10 Ma to 8 Ma. Then leopard-sized Paramachaerodus showed up around 8 Ma and held the ambush-and-slash niche for another three million years. (Salesa and others, 2010b)

Paramachaerodus had moderately long, serrated sabers. Its other sabertooth features were a little more developed than Promegantereon’s. (Salesa and others, 2010b; Turner and others)

Smaller saber-cats like these probably coexisted with lion-sized Amphimachairodus by sharing resources in some way that’s not well understood yet. (Werdelin and others)

Perhaps they took refuge in trees, just as modern leopards do today in lion and tiger country. (Antón; Domingo and others)

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Toward the end of the Miocene, Europe’s rich wildlife suffered a crisis that was probably related to global cooling. Barbourofelids and amphicyonid beardogs were among the casualties, but the Knife-Tooths came through it with just some reorganization. (Agustí ; Prothero, 2006; van den Hoek Ostende and others)

In the new Pliocene epoch, Paramachairodus was replaced by Megantereon – an undisputed member of the Smilodontini tribe. (Antón; Hunt, 2004; van den Hoek Ostende and others)

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Megantereon

This jaguar-sized saber-cat got around – ranging across Eurasia, Africa, and North America – but apart from the spectacular skeleton displayed above, few of its fossils have been discovered yet. (Antón; Zhu and others)

As a result, no one is sure when or where Megantereon evolved. (Antón; Zhu and others)

This matters a lot to paleontologists, because the most iconic sabertooth of all – Smilodon – appeared after Megantereon’s arrival.

Everybody, laypeople as well as scientists, wants to know where Smilodon – the dirk-toothed sabercat from California’s La Brea asphalt seeps and the only fossil cat to have appeared in a hit movie (Ice Age) – came from.

Some experts think that Megantereon traveled into North America from Asia and evolved into Smilodon around 2.4 Ma. (Hunt, 2004)

There are other possibilities, for instance, that Smilodon and Megantereon were two groups, or that they and another saber-cat that its discoverers have named Rhizosmilodon shared a common ancestor. (Wallace and Hulbert)

It’s even possible that Megantereon was in Africa around the time of Lokotunjailurus, long before it appeared on other continents. (de Bonis and others)

Anyway, here we are at last, some two and a half million years before the present. The Miocene is far behind us, snow is beginning to fall, and vast areas of the continental polar regions are icing over. (Agustí and Antón)

The most advanced cats to ever walk this Earth – Homotherium, Megantereon, and Smilodon – are now well established and at their peak.

To be continued tomorrow


Images:

Featured image: Megantereon cultridens, Natural History Museum, Basel, Switzerland: Ghedoghedo. CC Att SA 4.0 International. Partial.

Machairodus aphanistus, Museo Arqueológico Regional de la Comunidad de Madrid (Alcalá de Heneres).

Combined image:

  • Top: Proailurus, Cope, E. D. 1880. On the extinct cats of America. American Naturalist. xiv (12):833-857, figure 1.
  • Bottom: Machairodus. Ghedoghedo. SEE PAGE CC att SA 3.0 unported, 2.5 Generic, 2.5 Generic, and 1.0 Generic.

Leopard in tree: Siddarth Maheshwari. CC BY-SA 3.0.

Megantereon, Natural History Museum, Basel, Switzerland: Ghedoghedo. CC Att SA 4.0 International.


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This series on sabertooths was originally posted at my Robin Huntingdon blog about a year ago.


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