Category Archives: cats

The Evolution of Cats: 6: Nimravides and the Metailurini

It’s time to look at “the other sabertooths.”

Some of them are also called “false sabertooths.” (Antón)

Whether false or true, these now-extinct animals are giving scientists useful insights into the world of sabertoothed cats.

You probably haven’t heard of them.

Everybody knows Smilodon – the California state fossil and star of Ice Age. Quite a few laypeople recognize the name of Homotherium, too.

homotherium-profile
Homotherium’s teeth weren’t as long as Smilodon’s and it had a lighter build.

We met both of these and other popular sabertoothed cats last time.

But hardly anyone outside the Paleontology Department’s “cat” section has ever heard of Nimravides or the Metailurini.

As one noted geoscientist puts it:
“I am fond of saying that a geologist writes like a person overcoming very grave reservations. This is because no geologist can operate as an earth historian without continuously doubting such opinions—regardless of the accuracy of the observations upon which they are based. The realization of our uncertainty makes us uneasy, as does knowing that our explanations of the past are not more true, but only more plausible, than the stories told by creationists, extraterrestrialists, and other seers.” (Van Couvering)

When talking about fossil cats, paleontologists still have many “grave reservations” to overcome.

Very few of those issues came up last time, when we checked out the Homotheriini and the Smilodontini.

smilodon-cope
Smilodon, as the 19th century saw it.  This fossil sabertooth is still wildly popular in the 21st century.

Those sabertooths get a lot of attention from the public as well as researchers, and paleontologists have researched them in great detail. (Werdelin and others)
However, the two tribes weren’t the only toothy big cats around during the Miocene epoch and the Plio-Pleistocene ice ages.

No history of feline evolution is complete without mention of:

  • Nimravides. Long-legged and the size of a modern lion (Hunt, 2004), this was a mysterious North American saber-cat.
  • The Metailurini. Part sabertooth, part “normal” cat, these predators had a much wider range than Nimravides. Some of them were the most common Pliocene felids in Africa. (Werdelin and Dehghani)
632px-metailurus_metailurus_major_asenovgrad2
Metailurus is nowhere near as charismatic as Smilodon, but scientists are very curious about this cougar-like Miocene cat.  Was it a sabertooth or not?

 

Aside from the occasional complete skeleton, most of the other sabertooth fossils are fragments that can be interpreted in different ways. (Turner and Antón)

Of course this leads to lots of scientific controversy.

Yet the basic facts about Nimravides and the Metailurini are clear enough.

Both cat groups developed around the same time as the early members of the Homotheriini and Smilodontini. Then they coexisted with the two tribes for millions of years.

Nimravides didn’t make it out of the Miocene epoch (Werdelin and others), but the last member of the Metailurini died relatively recently, during the second half of the Pleistocene. (Werdelin and Dehghani)

All of them were very successful predators, and here is their story, as far as researchers have been able to outline it to date.

Continue reading The Evolution of Cats: 6: Nimravides and the Metailurini

 The Evolution of Cats:  4.  The First Cat

Last time, Silvester the African wildcat showed how our own housecat would live out in the wild . . . as long as the habitat was a place like the Kalahari plain in southern Africa.

Fluffy’s style would have to change if it lived in a swampy jungle or high up in the Andes.

Yes, there are small cats in the Andes. Andean mountain cats are rare and hard to study. (Sunquist and Sunquist)

Felids (members of the cat family Felidae) are up to the challenge. These very adaptable animals are found all over the world today.

They are also in the geologic record. For tens of millions of years cats have always:

  • Competed with each other in all these places
  • Hunted prey that was evolving rapidly and in diverse ways
  • Had sex and raised kittens
  • Coped as best they could with other community predators that ranged from prehistoric giant beardogs; through the very cat-like ancient nimravids and barbourofelids that we will meet next time; to today’s Homo sapiens.

That’s a lot of work. No wonder modern cats tend to be a little irritable!

This jaguar looks a little like the Joker!

Those interactions with the environment and with other living members of their communities have, of course, influenced the evolution of cats in many ways.

We need this broader post now to move beyond Silvester and take a very general look at how the first cats evolved.

Then, next time, we can meet some of them, starting with the sabertooths.

Now, ladies and gentleman, set aside some time for reading – this post does cover a central idea in my book, that the evolution of cats was an epic  – and step this way into the time machine . . .

(Mind the gorgon, the T. rex, and the angry quoll.)

Humble beginnings

Many of the complex feline features that we admire today actually evolved to meet a vital but simple need in the past.

Sometimes this need arose a very long time ago.

Believe it or not, a cat’s beautiful coat; its claws, whiskers, and teeth; and the glands it uses to advertise for a mate and to mark its territory all come from integument (Chuong and Harberger) – that is, from skin.

Cats are still recuperating from the evolutionary effort.

Integument first evolved in some of the oldest ancestors of mammals and reptiles.

Those former fish needed the outer covering to protect themselves from dehydration, now that they were spending more and more time out of the water.  (Alibardi)

Integument of various shapes and qualities also helped them slither around or pull themselves along as they colonized the land.  (Alibardi)

Today, molecular biologists say that things like claws and teeth come from the integument’s epithelial stem cells.

These cells can be organized in lots of different ways.  (Chuong and Harberger)

Exactly how this works isn’t well understood yet, but it has indeed led to the diversity of today’s animals. (Chuong and Harberger)

The development of integument is one of the points where the story of cat evolution (and much else) really begins.

We need to go back 350 million years for it (Benton and others) – a much longer span of time than the 65 million years or so that have passed since the K/T extinction of nonavian dinosaurs and some other forms of Cretaceous life.

A modern avian dinosaur poses with data from the geological record. Feathers developed from integument, too. (Chuong and Harberger)

We would have needed a time machine anyway.  Cats are mammals, after all, and the Linnean order Mammalia is very old.

You might have heard that the Age of Mammals began when nonavian dinosaurs went away.

Actually, that’s just the Cenozoic – sixty-five million years of what scientists who take the really long view call “recent life.”

Mammal beginnings are nowhere near as recent as that.

Mammals and dinosaurs

Two-thirds of the real Age of Mammals was already over (Kielan-Jaworowska) when a killer bolide suddenly appeared in Cretaceous skies.
Continue reading  The Evolution of Cats:  4.  The First Cat