Fossils, even awesome ones like that, can be disconcerting.
They remind us that nothing lasts forever, that almost all species that have ever lived are extinct.
But many of them had runs lasting millions of years, while Homo sapiens has only been around for a few hundred thousand years. We still have a ways to go.
So there’s that.
Too, fossils are so intriguing!
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 (see list of sources)
This is what
Indiana Jones 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.
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.
About geologic time . . .
Nimravids actually go back halfway to the K/T extinction.
Now, many of us have the impression that the Ice Age happened very long ago, soon after the K/T extinction ended the Age of Dinosaurs and started the Age of Mammals.
And before that, dinosaurs had been around since almost the start of Earth (“almost” because we have heard that there were lots of “-cenes” in geologic history; and that there was a Permian extinction, a Cambrian explosion of life, and Precambrian time before that, as well as much lava and changes in sea level).
We are also open-minded and wouldn’t be at all surprised to hear that this is a very incomplete and jumbled picture, which is indeed the case.
It’s beyond the scope of this post to say much more 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 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 on Earth.
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, but there was another group of sabertooths around for a while, too.
And they really carried saberteeth to extremes!
Paleontologists thought at first that these were Nimravids Version 2.0, but they overlapped in time with family Felidae, as we’ll see next week, and opinion is shifting more towards the view that these sabertooths might have related somehow to cats.
Edited September 6, 2020.
Featured image: Rama via Wikimedia, CC BY-SA 2.0.
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.