Repost: The “Other Sabertooths”


Here is one of the posts (revised) from my early 2018 series here on sabercats — beautiful creatures that I’d like to write an eBook about in a year or two from now.

You might have heard of Smilodon (of La Brea Tar Pit fame), but what about Nimravides and the Metailurini?

That sounds like a rock band, but these were two impressive and very different long-fanged feline groups:

  • Nimravides. Long-legged and at least the size of a modern lion (Antón; Hunt, 2004), this mysterious sabercat prowled North America during the late Miocene, some 10-12 million years ago.
  • The Metailurini. Part sabertooth, part “normal” cat, Metailurus and its possible tribe had a much wider range than Nimravides. Some of them were the most common Pliocene felids in Africa. (Werdelin and Dehghani)

Metailurus fossils aren’t as impressive as Smilodon’s, but this cougar-like Miocene cat was tough enough to thrive alongside the big sabercats. (Image: Izvora, via Wikimedia, CC BY-SA 3.0)


Very little is known about either group.

Scientific uncertainty

Of course, geoscientists don’t know much about many of the other things found while digging around in the earth, either.

On this blog, we don’t need to go into “iffiness” very often to get to Wonder. Still, it’s good to be aware that, as a 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 (see source list)

Paleontologists still have many “grave reservations” when discussing Nimravides and the Metailurini.

Yet the basic facts are clear enough.

Both cat groups developed around the same time as the early members of the Homotheriini and Smilodontini. Then they coexisted somehow with those impressive sabercats for a reasonably long time.

Nimravides didn’t make it out of the Miocene epoch (Werdelin and others), as far as anyone knows at this point.

The last member of the Metailurini died relatively recently, during the second half of the Pleistocene. (Werdelin and Dehghani)

All of these “other” sabertooths were very successful predators, and here is their story, as far as I understand what researchers have been able to outline to date.

Nimravides

Nimravides has not withstood the passage of time as well as Metailurus. This specimen is in the American Museum of National History. (Image: Ghedoghedo via Wikimedia, public domain)

Probably the least controversial way for a layperson to introduce this sabertoothed cat is to say that it first appeared in North America 12 to 14 million years ago. (Werdelin and others)

We’re on sure ground saying it “appeared” because Nimravides definitely shows up in the fossil record. (After all, “present” is almost the only fact that anyone really knows about any cat.)

More specifically, experts report that:

…at ~16.5-17 Ma [million years ago], the first felids enter[ed] North America from Eurasia and persist[ed] as relatively small, lynx- to leopard-sized cats until the appearance of the large lion-sized felid Nimravides…

— Hunt, 2004

A felid is any member of the cat family, Felidae. But there’s a little more to it than that, considering how many cats have roamed this planet down through geologic time.

Today’s group of cats is not the only one that has ever existed. There are at least two known subfamilies in Felidae:

  1. Felinae, sometimes called the “conical-toothed” cats. These are modern cats — the only ones left standing after Family Felidae first appeared in the early Miocene (or possibly late Oligocene)
  2. Machairodontinae: “Knife-tooths,” i.e., the sabercats. Contrary to what many people think, sabertooths were actually very successful, highly evolved, and had a good, 14-million-year run (Werdelin and others.) until the last species finally went extinct some 12,000 years ago at the end of the last ice age.

Some experts think that Nimravides may have represented yet a third subgroup. (Werdelin and others) If so, its fossils have only been found in North America, unlike those of the Knife-tooths and ancestral conical-toothed cats.

In life, Nimravides was indeed as big as a modern lion. It had a heftier build, though – like a tiger, with very long, muscular legs. (Antón, Figure 3.39; Hunt, 2004; Martin, 1980; Turner and Antón)

Nimravides also had saberteeth like those of Machairodus – the Old World sabertoothed cat that we met earlier in this series.


Is Fluffy being a nuisance today? Cheer up — had evolution gone differently, you might be dealing instead with “Machairodus giganteus”! Note the surprisingly small lower canines on that skull, by the way. (Image: coluberssymbol via Wikimedia)


The origin of Nimravides is where things get a little iffy again.

Around 12-14 million years ago, in the middle Miocene, did this cat:

  • Emerge first in Eurasia as Machairodus and then travel across the Bering land bridge into North America? (Antón)
  • Evolve locally from those early lynx- and leopard-sized felid immigrants to North America mentioned above by Hunt? (Werdelin and others)

No one knows for sure. (Werdelin and others)

The history of pseudaelurine cats is fairly well understood in Europe, and to a lesser degree in Asia (where there aren’t that many helpful outcrops from the right geological epoch, according to Werdelin and others), but paleontologists have yet to find Nimravides’ fossilized ancestor in North America, if it exists.

Supporters of the “Nimravides was a North American home boy” hypothesis offer some possible candidates – local pseudaelurine species, like P. intrepidus or P. marshi, that Nimravides resembles. (Werdelin and others)

This resemblance could mean that one of these Pseudaelurus species evolved into Nimravides.

But this doesn’t rule out the possibility that Nimravides was related to a Knife-tooth species of Machairodus that migrated into North America from Eurasia, across the Bering land bridge, around 7 Ma (million years ago). (Hunt, 2004)

Some paleontologists report there are enough resemblances between Nimravides and Machairodus fossils, including but not limited to the saberteeth, to show that the two cats may be related. (Antón and others)

It’s not impossible. What if Pseudaelurus quadridentatus, the probable ancestor of sabercats, originated in Asia back in the late Miocene, not in Europe where all of its fossils have been found so far? (Antón)

Then some individuals could have headed west into Europe and evolved into Machairodus. Others – the ancestors of Nimravides – might have traveled eastward over the Bering land bridge into North America. (Antón)

This alternative version works so well with one Nimravides species that experts have changed its name from Nimravides catocopis to Machairodus catocopis. (Antón and others; Fossilworks)

But for the other four recognized Nimravides species (Werdelin and others) . . . not so much.

Perhaps those species did descend from the early North American pseudaelurines. (Antón and others)

The scientific controversies over Nimravides will probably continue until paleontologists can establish just how the Pseudaelurus complex of cats got started, and what relationships there were among pseudaelurines in Europe, Asia, and North America. (Antón; Werdelin and others)

The Metailurini

Metailurus is often compared to a cougar (shown above).  Experts say you can’t get an accurate reconstruction by simply adding saberteeth to a modern animal, but it’s tempting. (Image: Tambako the Jaguar, CC BY-ND 2.0)

This group of prehistoric cats roamed Africa and the nothern continents for some nine million years. (Antón)

Paleontologists have lots of “grave reservations” about them, even though the Metailurini lived much closer to our own time than Nimravides did.

First, despite their closeness to us in time, there aren’t very many fossils available. And interpretations of what fragmentary evidence there is often vary from researcher to researcher. (Antón)

Everybody does accept these two Metailurini groups:

  • Metailurus. Ranging in size from a modern snow leopard to a large cougar, this Miocene cat apparently evolved in Eurasia. (Werdelin and others) It had moderately long, flat upper canines and was slightly more advanced than P-Quad, which it resembled. (Antón)
  • Dinofelis. This cat probably first showed up in Africa (Werdelin and Lewis) and then traveled to Eurasia and North America. (Turner and Antón) It was generally bigger than Metailurus, up to small-lion in size. (Antón) More muscular than a modern leopard, Dinofelis had the same overall proportions. Some species had moderately flat but not very long saberteeth; others had almost “normal” teeth, like today’s conical-toothed big cats. (Werdelin and Lewis)

Just for the record, other groups associated with the Metailurini are Adelphailurus, Stenailurus, Pontosmilus, and Fortunictis. (Antón; Berta and Galiano; Werdelin and others)

However, things quickly get very technical when you start looking into those names, so let’s just move on to Metailurini controversies that are easier for laypeople like us to understand.

For example, where did these cats come from? The pseudaelurine cats apparently had disappeared before the Metailurini arrived.

Even if we just look at Metailurus and Dinofelis, nobody knows how they evolved or whether they were even closely related to each other. (Werdelin and others)

Their evolution was centered on different continents — North America, for Metailurus; Africa, for Dinofelis.

Too, Dinofelis was most successful during the Pliocene and Pleistocene epochs. Metailurus had its heyday in the Miocene, millions of years earlier. (Werdelin and others)


This is only labeled “sabre-toothed cat” by the photographer, but based on what I’ve read, it’s probably Dinofelis. Note that no fur of any sabercat has survived, so paleontologists just make an educated guess about such details in a reconstruction. (Image: Flowcomm), CC BY-SA 3.0)


Some paleontologists suspect Metailurus may have given rise to Dinofelis. (Beaumont, quoted by Werdelin and Lewis)

Others just group these two together because they were clearly different from modern cats but didn’t have enough sabertooth features to qualify for Machairodontinae. (Werdelin and others)

Were Metailurus and Dinofelis Knife-tooths with only slight to moderate saberteeth, or were they “normal” cats (conical-tooths) with a tendency toward a few sabertooth characteristics? (Antón; Werdelin and others)

No one can say for sure yet.

Only one thing is clear – when it came to saberteeth, Dinofelis just couldn’t make up its mind.

The oldest and youngest Dinofelis species were definitely sabertooths (Werdelin and others), but some species in between had upper canines that weren’t much different from those you’ll see in today’s lion. (Werdelin and Lewis)

In fact, one species –Dinofelis cristata – may be the only known case where a sabertoothed cat switched over to “normal” upper canine function! (Werdelin and Lewis)

This flexibility – going from sabertooth to “normal” back to sabertooth again – leads some paleontologists to suspect that Knife-Tooths and “normal” cats competed much more directly than previously thought. (Turner and others)

We don’t know exactly how they hunted, but the sabertooths probably went after big prey (Antón; Turner and others), leaving smaller prey to the “normal” cats that were also evolving back then. (Werdelin 1989)

Theoretically, the two groups of cats could have easily shared resources because their hunting techniques were different.

But the variability in Dinofelis teeth may show that cats had more hunting options than just “sabertooth” and “normal.” (Turner and others)

This in turn could mean that conical-toothed cats interacted with the Knife-tooths in many ways, and vice versa. (Turner and others; Werdelin and others)

It’s even possible that some modern cat species may have been one of the culprits behind the sabertooth extinction at the end of the last ice age!


These guys, most likely. (Image: William Warby, CC BY 2.0)

It’s not just about saberteeth

When you get right down to it, besides their basic “catitude”, Metailurus and Dinofelis had only one physical detail in common: unusually small lower fangs. (Turner and others)

And this obscure dental detail, according to some researchers, may eventually prove beyond question that the Metailurini were Knife-tooths.

Most of us go by the sabers when defining a sabertoothed cat.

However, as we saw last time, there is also a “sabertooth complex” of physical features that include a more powerful body and, of crucial importance to us here, a arch of very large incisors. (Antón)

Paleontologists know that, as the upper canines turn into saberteeth and the incisors get bigger, lower canine fangs usually get smaller to match the incisors.

The saberteeth are obvious (and terrifying!) on this reconstruction of “Barbourofelis loveorum” — part of an ancient group of sabertooths that predated Knife-tooths and may or may not have been felids (Werdelin and others.) Note, though, that you can’t tell the difference between its incisors and lower fangs (and no, they’re not obscured by that protective flange that sheaths the saberteeth). (Image: Dallas Krentzel, CC BY 2.0)

A researcher now says that the size of lower canine teeth may be more important than sabers when it comes to sorting out sabertoothed cats.

He ran an advanced computer analysis on selected sabertooth fossil features to see what patterns showed up among the different sabertoothed cats. (Christiansen)

Surprisingly, the conventional groups of Homotheriini, Smilodontini, and Metailurini didn’t show up. (Christiansen)

Instead, Metailurus and Dinofelis, as well as Nimravides – and even Machairodus and Promegantereon! – were all linked together, mostly because their lower canines were all reduced in size. (Christiansen)

Dr. Christiansen calls these cats the Machairodontinae (Knife-Tooths). He uses the name Eumachairodontinae (True Knife-tooths) for the later saber-cats, including Megantereon, Smilodon, Amphimachairodus, Homotherium, and Xenosmilus, who sported “true” saberteeth.

This view is not widely accepted yet, and there are some criticisms. (See Spassov and Geraads, “Cladistic Analysis”)

We’ll have to see how this idea turns out over time.

But it’s a good example of how paleontologists are using some very advanced tools these days to learn more about the evolution of cats.


“Here, kitty, kitty . . .” (National Park Service, public domain)


Featured image: Metailurus major, cranial detail. Izvora, via Wikimedia, CC BY-SA 3.0.


Cited and uncited 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.

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

Antón, M.; Salesa, M. J.; and Siliceo, G. 2013. Machairodont adaptations and affinities of the holarctic late Miocene homotherin Machairodus (Mammalia, Carnivora, Felidae): The case of Machairoidus catocopis (Cope, 1887). Journal of Vertebrate Paleontology. 33(5):1202-1213.

Barnett, R.; Barnes, I.; Phillips, M. J.; Martin, L. D.; Harington, C. R.; Leonard, J. A.; and Cooper, A. 2005. Evolution of the extinct sabretooths and the American cheetahlike cat. Current Biology, 15(15):R589-R590.

Barnosky, A. D. 2001. Distinguishing the effects of the Red Queen and Court Jester of Miocene mammal evolution in the northern Rocky Mountains. Journal of Vertebrate Paleontology. 21(1):172-185.

Benton, M. J.; Donoghue, P. C. J.; Asher, R. J.; Friedman, M.; Near, T. J.; and Vinther, J. 2015. Constraints on the timescale of animal evolutionary history. Palaeontologia Electronica, 18.1.1FC 1-106. palaeo-electronica.org/content/fc-1.

Benton, M. J. 2009. The Red Queen and the Court Jester: Species diversity and the role of biotic and abiotic factors through time. Science. 323(5915):728-732. Abstract.

Berta, A., and Galiano, H. 1983. Megantereon hesperus from the Late Hemphillian of Florida with remarks on the phylogenetic relationships of machairodonts (Mammalia, Felidae, Machairodontinae). Journal of Paleontology. 57(5):892-899.

Best, M. G.; Barr, D. L.; Christiansen, E. H.; Gromme, S.; Deino, A. L.; and Tingey, D. G. 2009. The Great Basin Altiplano during the middle Cenozoic ignimbrite flareup: insights from volcanic rocks. International Geology Review. 51:7-8, 589-633.

Cain, M. L.; Bowman, W. D.; and Hacker, S. D. 2014. Ecology. Sunderland, Massachusetts: Sinauer Associates.

Chapin, C. E., Wilks, M., and McIntosh, W. C. 2004. Spacetime patterns of Late Cretaceous to present magmatism in New Mexico – comparison with Andean volcanism and potential for future volcanism. New Mexico Bureau of Geology and Mineral Resources, Bulletin 160:13–40. Socorro, New Mexico.

Christiansen, P. 2013. Phylogeny of the sabertoothed felids (Carnivora: Felidae: Machairodontinae). Cladistics, abstract. 29: 543–559.

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

Domingo, M. S.; Domingo, L.; Badgley, C.; Sanisidro, O.; and Morales, J. 2013. Resource partitioning among top predators in a Miocene food web. Proceedings of the Royal Society B. 280:2012-2138.

Driscoll, C. A.; Menotti-Raymond, M.; Roca, A. I.; Hupe, K.; Johnson, W. E.; Geffen, E.; Harley, E. H.; Delibes, M.; Pontier, D.; Kitchener, A. C.; Yamaguchi, N.; O’Brien, S. J.; and Macdonald, D. W. 2007. The Near Eastern origin of cat domestication. Science. 317:519-522.

Ezard, T. H. G.; Aze, T.; Pearson, P. N.; and Purvis, A. 2011. Interplay between changing climate and species’ ecology drives macroevolutionary dynamics. Science. 332(6027):349-351.

Farris, D. W.; Jaramillo, C.; Bayona, G.; Restrepo-Moreno, S. A.; and others. 2011. Fracturing of the Panamanian Isthmus during initial collision with South America. Geology. 39(11):1007-1010.

Fossilworks. Machairodus catocopis Cope 1887 (cat). http://fossilworks.org/bridge.pl?a=taxonInfo&taxon_no=47841.

Gradstein, F. M.; Ogg, J. G.; and Hilgen, F. G. 2012. On the geologic time scale. Newsletters on Stratigraphy. 45(2):171-188.

Heske, E. J. Fall 2013 semester. Mammalogy 462, online class notes. Multiple lectures. http://www.life.illinois.edu/ib/462 . Last accessed December 11, 2015.

Hunt, Jr., R. M. 1989. Biogeography of the Order Carnivora, in Carnivore Behavior, Ecology, and Evolution, ed. J. L. Gittleman, J. L., 2:485–541 Ithaca, NY: Cornell University Press.

—. 2004. Global climate and the evolution of large mammalian carnivores during the later Cenozoic in North America. Bulletin of the American Museum of Natural History. 285:139-156.

Jaramillo, C.; Montes, C.; Cardona, A.; Silvestro, D.; and others. 2017. Comment (1) on “Formation of the Isthmus of Panama” by O’Dea and others. Science Advances. 3:e.1602321.

Johnson, W. E.; Eizirik, E.; Pecon-Slattery, J.; Murphy, W. J.; Antunes, A.; and Teeling, E. C. 2006. The Late Miocene Radiation of Modern Felidae: A Genetic Assessment. Science 311:73-77.

Kitchener, A. C., Van Valkenburgh, B., and Yamaguchi, N. 2010. Felid form and function, in Biology and Conservation of Wild Felids, ed. D. W. Macdonald and A. J. Loveridge, 83-106. Oxford: Oxford University Press.

Kohn, M. J., and Fremd, T. J. 2008. Miocene tectonics and climate forcing of biodiversity, western United States. Geology, 36 (10):783-786.

Martin, L. D. 1980. Paper 287: Functional Morphology and the Evolution of Cats. Transactions of the Nebraska Academy of Sciences and Affiliated Societies. VIII:141-154.

Nyakatura, K., and Bininda-Emonds, O. R. P. 2012. Updating the evolutionary history of Carnivora (Mammalia): a new species-level supertree complete with divergence time estimates. BMC Biology. 10:12.

O’Brien, S. J. and Johnson, W. E. 2007. The evolution of cats. Scientific American. 297 (1):68-75.

O’Brien, S. J.; Johnson, W.; Driscoll, C.; Pontius, J.; Pecon-Slattery, J.; and Menotti-Raymond, M. 2008. State of cat genomics. Trends in Genetics. 24(6):268-279.

Prothero, D. R. 2004. Did impacts, volcanic eruptions, or climate change affect mammalian evolution? Palaeogeography, Palaeoclimatology, Palaeoecology. 214:283-294.

—. 2006. After the Dinosaurs: The Age of Mammals. Bloomington and Indianapolis : Indiana University Press.

—. 2012. Cenozoic mammals and climate change: The contrast between coarse-scale versus high-resolution studies explained by species sorting. Geosciences. 2:25-41.

Ravelo, A. C.; Andreasen, D. H.; Lyle, M.; Olivarez Lyle, A.; and Wara, M. W. 2004. Regional climate shifts caused by the gradual global cooling in the Pliocene epoch. Nature. 429:263-267.

Rothwell, T. 2003. Phylogenetic Systematics of North American Pseudaelurus (Carnivora: Felidae). American Museum Novitates. 3403:1-64.

Salesa, M. J., Antón, M., Morales, J., and Peigné, S. 2011. Functional anatomy of the postcranial skeleton of Styriofelis lorteti (Carnivora, Felidae, Felinae) from the Middle Miocene (MN 6) locality of Sansan (Gers, France). Estudios Geológicos, 67(2):223-243.

Salesa, M. J.; Antón, M.; Turner, A.; and Morales, J. 2010a. Functional anatomy of the forelimb in Promegantereon ogygia (Felidae, Machairodontinae, Smilodontini) from the the late Miocene of Spain and the origins of the sabre-toothed felid model. Journal of Anatomy. 216:381-396.

Salesa, M. J.; Antón, M.; Turner, A.; Alcala, L.; Montoya, P.; and Morales, J. 2010b. Systematic revision of the late Miocene sabre-toothed felid Paramachaerodus in Spain. Palaeontology. 53(6):1369-1391.

Smithsonian National Museum of Natural History. Geologic Time: The Story of a Changing Earth. http://paleobiology.si.edu/geotime/main/ Last accessed in summer of 2015.

Spassov, N., and Geraads, D. 2015. A new felid from the Late Miocene of the Balkans and the contents of the genus Metailurus Zdansky, 1924 (Carnivora, Felidae). Journal of Mammal Evolution. 22:45-56.

Sunquist, M. and Sunquist, F. 2002. Wild cats of the world. Chicago and London: University of Chicago Press.

Turner, A., and Antón, M. 1997. The Big Cats and Their Fossil Relatives: An Illustrated Guide to Their Evolution and Natural History. New York: Columbia University Press.

Turner, A., Antón, M., Salesa, M. J., and J. Morales, J. 2011. Changing ideas about the evolution and functional morphology of Machairodontine felids. Estudios Geológicos. 67(2): 255-276.

Van Couvering, J. A. 1989. Introduction to Catastrophes and Earth History: The New Uniformitarianism, ed. Berggren, W.A. and Van Couvering, J.A., editors. Princeton: Princeton University Press.

van den Hoek Ostende, L., Morlo, M., and Nagel, D. 2006. Fossils explained (52): Majestic killers: the sabretoothed cats. Geology Today. 22(4):150-157.

Van Valkenburgh, B. 1999. Major patterns in the history of carnivorous mammals. Annual Reviews of Earth and Planetary Science. 27:463-493.

—. 2007. Déjà vu: the evolution of feeding morphologies in the Carnivora. Integrative and Comparative Biology. 47 (1):147-163.

Werdelin, L. 1989. Carnivoran Ecomorphology: A Phylogenetic Perspective, in Carnivore Behavior, Ecology, and Evolution, ed. Gittleman, J. L., 2:582-624. Ithaca, NY: Cornell University Press.

Werdelin, L., and Dehghani, R. 2011. Carnivora, in Paleontology and Geology of Laetoli: Human Evolution in Context, Volume 2: Fossil Hominins and the Associated Fauna, Harrison, T., ed., 189-232. Springer, Dordrecht.

Werdelin, L., and Lewis, M. E.  2001.  A revision of the genus Dinofelis (Mammalia, Felidae). Zoological Journal of the Linnean Society. 132: 147–258.

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, ed. D. W. Macdonald and A. J. Loveridge, 59-82. Oxford: Oxford University Press.


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





Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.