Nimravids: An Introduction Only


Paleontologists seldom write up their finds in poetry, but as you can see, this 1932 find was a little different.

That is cat-like Nimravus, who got its sabertooth stuck in the shoulder blade (scapula) of one of its fellows during a fight some 40 million years ago in what’s now Nebraska.


Once in the sun-fierce badlands of the west
in that strange country of volcanic ash and cones,
runneled by rains, cut into purgatorial shapes,
where nothing grows, no seeds spring, no beast moves,
we found a sabertooth, most ancient cat,
far down in all those cellars of dead time.
What was it made the mystery there? We dug
until the full length of the striking saber showed
beautiful as Toledo steel, the fine serrations still
present along the blade, a masterpiece of murderous art conceived
by those same forces that heaved mountains up
from the flat bottoms of Cretaceous seas.

Attentive in a little silent group we squatted there.
This was no ordinary death, though forty million years
lay between us and that most gaping snarl.
Deep-driven to the root a fractured scapula
hung on the mighty saber undetached; two beasts
had died in mortal combat, for the bone
had never been released; there was no chance
this cat had ever used its fangs again or eaten—
died there, in short, though others of its kind
grew larger, larger, suddenly were gone
while the great darkness went about its task,
mountains thrust up, mountains worn down,
till this lost battle was exposed to eyes
the stalking sabertooths had never seen…

From Lauren Eiseley’s “The Innocent Assassins (PDF download)


Nimravus gave its name to this entire group of cat-like predators — the nimravids.

But they weren’t cats, as far as anyone knows. It’s not even clear how they evolved, though the where of it might have been Asia (jargon alert).

Just suddenly! There are the very first cat-like predators ever, going about their business and leaving fossils in Eocene/Oligocene North America.

I imagine the region’s beardogs, bone-crushing dogs, and hyaenodonts (the last two coming in tomorrow’s post) weren’t thrilled by that, but they had to adapt. The nimravids were very successful here and elsewhere in the world, finally going extinct in North America just a few million years before a true cat — one of the pseudaelurine descendants of the Dawn Cat — wandered in from Europe or Asia over a land bridge.

There aren’t any good videos on nimravids, unfortunately. Here are some posts on nimravids by Mauricio Antón.

I also dug up one of my blog posts and heavily edited it:


Sometimes old-time science did take the Indiana Jones approach.


The exploring party which I had sent into the John Day River valley under the direction of Mr. Jacob L. Wortman, in 1879, examined the bad-lands in the locality known as The Cove. In passing the bluffs on one occasion, a member of the party saw on the summit of a pinnacle of the crag what appeared to be skull. The large shining objects supposed to be teeth attracted his attention, and he resolved to obtain the specimen. He, however, was unable to climb the cliff, and returning to camp narrated the circumstance. The other men of the party successively attempted to reach the object, but were compelled to descend without it, and in one case, at least, the return was made at considerable peril. A later attempt, made by Leander S. Davis, of the party, an experienced collector, was more successful. By cutting notches with a pick, in the face of the rock, he scaled the pinnacle and brought down the skull, but at considerable risk to limb and life.

— E. D. Cope, 1880, page 848


This is what Mr. Davis brought back:



E. D. Cope named this animal “Pogonodon” and called the group it belonged to “nimravids.” Both terms are still used today.


A sabertoothed cat!

Well, that’s what Cope and other expert paleontologists thought at the time. Further research has cast doubt on it, although the question of exactly what nimravids were and where they came from is still under debate.

Even with the limited information available to them, early paleontologists could see that nimravids are much older than the sabercats, which is why some experts used the misnomer “paleofelids” for them.

The fossils of Pogonodon and/or its relatives come from deposits in Europe and Asia, as well as North America, that are many tens of millions of years older than those in which Smilodon and Homotherium fossils lurk.

And they appear fully formed, without any clues as to how they acquired saberteeth and their surprisingly cat-like build.

It’s quite a mystery.


Figure 45 in Barrett, listing nimravid species and suggesting possible relationships among them. CC BY-SA 4.0.


I can’t do the individual nimravid groups justice, though you can see by the skulls up there that they came in quite a variety.

Nimravids typically ranged from lynx to lion in size.



Nimravids didn’t have such long legs, though, and many were a little flat-footed compared to modern cats. They probably hunted mostly by ambush, though they could sprint short distances.


Check out the source list, if you are curious about the details and don’t mind wading through technicalities.

Bryant presents a good overview of North American nimravid species. Peigne provides the European view as well as an excellent review of changing paleontological views of them down through the years.

Anton, a paleoartist as well as author, uses the least jargon and also presents beautiful reconstructions of creodonts, nimravids, and other sabertooths.

Of course, nimravids weren’t operating in a vacuum. Janis and Prothero look at the big picture, with Prothero’s book being very detailed and mostly in plain English.

Nimravids in time . . .

Nimravids actually go back halfway to the K/T extinction.

It’s beyond the scope of this post to say much about geologic time, as I understand it, other than that the Sun has been rising in the east and setting in the west, as it does now, for an unfathomably long time.

Uncounted days and nights have passed on Earth as animals, plants, and what’s-its appeared, interacted with each other and with the planet, and then vanished — roughly 99% of them anyway — after passing on a very complex heritage to the other 1% (us and the rest of today’s life).

As for nimravids and sabercats, let’s just go with a very imprecise analogy.

Imagine an analog clock.

Mammals and dinosaurs evolved together about five hours ago.



Some three weeks of earth history, in our analogy. Mammals and dinosaurs first appeared in the Triassic. And there was more than one recent ice age, though that wouldn’t show up on this scale (see below).


The K/T extinction happened an hour ago. And:

  • Ancestors of what is now the order Carnivora showed up around five minutes later, along with their “cousins” the Creodonts (who let in a couple sabertooths at 10 after).
  • The nimravid party began just before the half-hour and ended about twenty minutes ago.
  • The first known sabercat entered the room 14 minutes ago.
  • Two and a half minutes ago, the North Pole froze up and ice ages began. There have been at least a dozen ice ages since, with H. sapiens arriving at some point during or in between the last two. Smilodon and Homotherium — the last and most highly developed sabercats — went extinct several seconds ago, along with other megafauna (except in Africa, for some reason), when the last ice age ended.

Take-away #1: There were cat-like sabertoothed nimravids prowling around Asia, North America, and Europe LONG before true sabercats showed up. That’s amazing!

Take-away #2: Nimravids, creodonts, and many, many other land mammals thrived for millions of years, dominating the landscape. But they were “archaic,” leaving behind no modern descendants. Their era, which ended at the close of the Oligocene some 24 minutes ago (24 million years ago) is called the Paleogene (Pg), while everything that came afterwards, starting in the Miocene, building the modern world, is known as the Neogene.

Cats are Neogene animals. They face different problems, including but not limited to —




Featured image: James St. John via Wikimedia, CC BY-SA 2.0.


Sources:

Agustí, J., and Antón, M. 2002. Mammoths, sabertooths, and hominids: 65 million years of mammalian evolution in Europe. New York and Chichester: Columbia University Press. doi:10.1126/science.1073295.

Antón, M. 2013. Sabertooth. Bloomington: Indiana University Press.

Barrett, P. Z. 2016. Taxonomic and systematic revisions to the North American Nimravidae (Mammalia, Carnivora). PeerJ. 4:31658.

Bryant, H. N. 1991. Phylogenetic relationships and systematics of the Nimravidae (Carnivora). Journal of Mammalogy, 72(1):56-78

Cope, E. D. 1880. On the Extinct Cats of America. American Naturalist. xiv (12):833-857

Holliday, J. A., and Steppan, S. J. 2004. Evolution of hypercarnivory: the effect of specialization on morphological and taxonomic diversity. Paleobiology. 30(1):108-128.

Peigné, S. 2003. Systematic review of European Nimravinae (Mammalia, Carnivora, Nimravidae) and the phylogenetic relationships of Palaeogene Nimravidae. Zoologica Scripta. 32(3):199-299.

Prothero, D. R. 2006. After the Dinosaurs: The Age of Mammals. Bloomington and Indianapolis : Indiana University Press.

Van Valkenburgh, B. 1999. Major patterns in the history of carnivorous mammals. Annual Review of Earth and Planetary Sciences. 27:46393.

___. 2007. Déjà vu: the evolution of feeding morphologies in the Carnivora. Integrative and Comparative Biology. 47 (1):147163.




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