BJ Deming

Writing Update: Cats and Dogs Edition

Doggie want a bone?

Doggie gonna need a tank and heavy infantry/artillery backup to get a bone from that cat, whose scientific name means “He who brings devastation (populator), tooth shaped like a double-edged knife (Smilodon)”!

But Doggie, an extremely close relative of gray wolves that have hunted down through the Pleistocene and into our time, is alive and walking around today, unlike fossil Smilodon or its many felid relatives and other cat-like sabertooths that have occasionally terrorized life on Earth ever since T. rex & Co. went away.

These hyperdental mammalian predators have left a few tracks for us, from the Oligocene —

Possibly the nimravid Eusmilus, per Bennett et al. (Image: Figure 4, Bennett et al., CC BY-NC-SA 4.0)

— and the last ice age:

Of known fossil animals, only Smilodon populator could have made these 6.9 x 7.6 inch feline tracks in Pleistocene South America, per Agnolin et al. (Image: Grupopaleowiki via Wikimedia, CC BY-SA 4.0)

— but no one knows very much about them.

Sabertooths are cool, though, and we should briefly meet them.

A new Friday series

As mentioned here and there in these posts, I originally planned, some ten years ago, to write a book on how cats evolved.

But it took time to develop writing skills — an ongoing effort — and to read up on the topic. PBS beat me to it (and did a much better job than I could) with “Cat Tales.”

But that was all about Felidae: the living conical-toothed cats and their ancestors, whose undomesticated body plan closely resembles that of the original fossil cat, Proailurus.

My reading had shown me that there was another branch on the Felidae family tree, called Machaerodontinae, “Knife-tooths,” as well as two older groups of very cat-like sabertooths (barbourofelids and nimravids).

Cat-relevant part of the geologic time scale, with our time — the Holocene– marked with a blue-spectrum line. (Source, public domain>

The nimravids, in fact, going all the way back to Eocene times long before Proailurus, are the first known fossil animals with a cat-like form (one that includes retracted claws, if you check out the Eusmilus footprints up there!) although no one yet has figured out how they got it (Bennett et al.; Werdelin et al.)

That’s why nimravids were labeled, incorrectly,”paleofelids” for a while, with barbourofelid and Family Felidae (living and extinct) were supposed to be “neofelids.”

Now all three are seen differently and their possible interrelationships are subjects of much debate.

We have explored these three groups — Machaerodontinae, Barbourofelidae, and Nimravidae — in a few posts here at the blog, but it’s a big subject and I didn’t think of getting into it in any detail until now, while considering topics for Feline Friday summer posts.

Why not sabertooths?

Well, mainly because I’m deeply committed to the two supervolcano projects — the post series on active ones listed by De Silva and Self, and a self-published eBook, The Supervolcanoes and Us, that I’d like to complete by year’s end.

But woman does not live by volcanism alone, and the Friday and Saturday posts are so much fun to do (hope you’re enjoying them, too).

That “guest-video” approach is not so tough that it distracts me from the volcano writing.

It’s actually refreshing and makes a nice break — I get to watch even more videos than the ones included in posts, and more and more good videos seem to come out all the time!

Trouble is, there aren’t that many accurate sabertooth videos on YouTube, and most of those are about Smilodon. There’s so much more, even if we just stayed in the cat family.

Covering sabertooths, therefore, involves more writing and that hasn’t seemed possible until now.

Fortunately, I’ve thought of a format that will not be in-depth, except for Smilodon and Homotherium, but will be tolerably accurate thanks to the sources that I’m reading anyway in my down time.

Most importantly, it can introduce you — that’s all — to the wonderful world of sabertooths.

It’s sort of a “baseball-card” approach, with a picture and a few facts about the animal and its world, mainly as reported by:

The only problem is that the information is a little dated.

My reading on sabertooths and paleontology has from sources published in the Oughts and Teens, and I can’t do an update on it right now.

So little is known about earlier parts of what most of us still call the Age of Mammals — geoscientists know it as the Cenozoic — that one new piece of evidence or a new interpretation of already documented fossils can be a game changer.

Perhaps the game has changed in one or more ways since I last checked it out, and so the facts in these posts might be outdated, just like the term “paleofelid.”

Does that really matter here?

All that most of us laypeople know is Smilodon and maybe its Pleistocene cousin Homotherium.

Let’s just take a quick look at these two plus some of the many other sabertoothed cats and cat-like mammals as they were known when I first learned about them.

Then you’ll at least have a basis to start with if you’re curious and want to look into it further.

Smilodon and Homotherium will book-end the series, which is going to extend into November.

Yes, there were that many sabertoothed cats and feliforms, and that’s only counting the known ones in the fossil record!

The Smilodon post is long — in part, because this fossil cat lived recently enough to leave behind a fair amount of evidence.

Also, everybody loves and is fascinated by Smilodon.

Exhibit A

Exhibit B is not so family-friendly:

Now where does Doggie come into it?

Natural vs. artificial selection

Sabercats are the products of natural selection, but artificial selection by H. sapiens is responsible for the doggos (that’s a little complicated).

Both kinds of selection can have dramatic results.

Natural selection

Sabercats in general — and Smilodon, as well as Homotherium, the last two sabertooths, in particular — were what boffins call “highly derived.”

This means that their evolutionary body plan (not just their lengthy upper canines) was much more developed than that of the OG cat Proailurus, while still being overall cat-like (both were members of Family Felidae, after all).

That is exactly opposite to what many of us still think of them, based on vague impressions we might have picked up of the 19th-century view that sabercats were evolutionary dead ends, their oversized teeth and skeletal changes probably contributing to extinction by disease and starvation.

That view is no longer tenable after many decades of research and the discovery of more and more fossils from all over the world.

The blue-spectrum line is pointing at the Pleistocene, Smilodon’s time. (Source, public domain)

We can’t be sure why the sabercats, and many large animals, went extinct as the Pleistocene ended and our own time — the Holocene — began.

Humans, climate change, and/or a combination of the two are possible causes, but it definitely wasn’t because the sabertooths were backward.

In automotive terms, they were Ferraris, but the Holocene called for a return to Ford Model T’s for some reason.

And then there are dogs.

Artificial selection

The domestic dog has the distinction of being the only known animal to be domesticated by humans prior to the advent of agriculture. As such, dogs are not only man’s best friend in the animal kingdom, but also his oldest one. Though the precise origin of dogs was a mystery in Darwin’s day, Darwin drew on them as an example of artificial selection that would be familiar to his readers, since the practice of shaping breeds over time was familiar to his audience:

But when we compare the dray-horse and race-horse, the dromedary and camel, the various breeds of sheep fitted either for cultivated land or mountain pasture, with the wool of one breed good for one purpose, and that of another breed for another purpose; when we compare the many breeds of dogs, each good for man in very different ways… We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed, in several cases, we know that this has not been their history. The key is man’s power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to make for himself useful breeds.

Note that Darwin is careful to point out that the variation itself is due to heredity: while humans can “add up” variation over time through selective breeding, they cannot produce the variation upon which they act. This point was important for Darwin to make, since he would later argue that natural selection also acts on that same heritable variation over time in a cumulative way.

— Source

That educational point — as well as the delicious contrast with Friday’s long-fanged wild felids — is why our Saturdays this summer and fall are going to feature guest videos about the American Kennel Club’s top 20 breeds of 2024.

Woof!

Today is Friday. Got yer safari helmet and night vision specs? Water bottle and munchies? Infantry and artillery notified and ready, just in case? Are we all buckled in?

Then let’s go!

Featured image: Smilodon, by JJonahJackalope via Wikimedia, CC BY-SA 4.0; English Springer Spaniel by Jurriaan Schulman via Wikimedia, CC BY-SA 3.0.

Sources:

  • Agnolin, F. L.: Chimento, N. R.; Campo, D. H.; Magnussen, M.; and others. 2019. Large carnivore footprints from the late Pleistocene of Argentina. Ichnos, 26(2), 119-126.
  • Bennett, C. J.; Famoso, N. A.; and Hembree, D. I. 2025. Following their footsteps: Report of vertebrate fossil tracks from John Day Fossil Beds National Monument, Oregon, USA. Palaeontologia Electronica, 28(1), 1-17.
  • Werdelin, L.; Yamaguchi, N.; Johnson, W. E.; and O’Brien, S. J.. 2010. Phylogeny and evolution of cats (Felidae), in Biology and Conservation of Wild Felids, eds. Macdonald, D. W., and Loveridge, A. J., 59-82. Oxford: Oxford University Press.

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