Repost: “False” sabertooths and real sabercats


Here’s a post from 2017, edited this week, that shows the direction I eventually plan to move in with feline Friday posts; however, look for occasional information about Fluffy, too — am revising the two domestic cat books right now!

Fact: Before sabercats, there were sabertoothed cat-like apex predators called barbourofelids and nimravids.



Does it matter if that ferocious sabertooth lacks the right bone structure to convince scientists it’s a cat?

Yes, if you are a paleontologist or other expert in ancient life — real life, that is, not CGI.

Luckily, we are secure against all things sabertooth today and can safely check out the three major long-toothed “cat” groups that have terrorized the planet at various times since the dinosaurs went away.

Sabertoothed cats

Paleontologists classify sabercats as Machairodontinae – “Knife-Tooths.” (Antón; Turner and others)

They were one of two subgroups in family Felidae that roamed the Earth from at least early Miocene times up until the last ice age ended. Only the subgroup Felinae exists today.

That reconstructed machairodont in the image at the top of this post is Smilodon fatalis, the famous sabertooth from California’s La Brea “tar” pits.

Unlike the other Ice-Age sabercat – Homotherium – Smilodon was strictly a New World animal. (Antón; Hulbert and Valdes)

The old idea that sabertoothed cats were too primitive to survive is wrong.

Knife-Tooths were very successful cats, with a run of at least twelve million years before they disappeared forever in the end-Pleistocene extinctions. (Agustí and Antón; Antón; Turner and Antón)

Barbourofelidae

Barbourofelis fricki, Museo di Paleontologia di Firenze, by Ghedoghedo via Wikimedia, CC BY-SA 3.0 (modified by me).

Barbourofelis fricki was the last, and biggest, of a long line of cat-like “false” sabertooths that lived in Europe, Asia, Africa, and North America during the second half of the Miocene epoch. (Antón; Bryant)

These barbourofelids were apex predators that both subgroups of the first true cats had to face, millions of years ago.

The jury is still out on possible connections, if any, to the cat family.

Barbourofelids were short-faced hypercarnivores similar to true cats, with much the same build. (Antón; Werdelin and others)

However, their fossils are just different enough from cats for experts to keep them in a separate family for now. (Bryant; Werdelin and others)

Nimravids

The nimravid Eusmilus, by Dallas Krentzel via Wikimedia, CC BY 2.0

.

Imagine a housecat with teeth like that. Yikes!

Yet that’s roughly the size of Eusmilus cerebralis, back in the Oligocene geological epoch. (Antón)

Eusmilus and other nimravids, some of which were very large, are the oldest group of cat-like “false” sabertooths.

In many ways, nimravids outdid the true sabercats. Besides having big sabers in very small animals (Eusmilus) — something that has never happened in family Felidae, as far as we know — nimravids also had more specialized cranial and body anatomy features that support a sabertooth lifestyle. (Werdelin)

That’s strange, because nimravids are very old and evolution doesn’t typically reverse itself. (Antón; Bryant; Agustí and Antón; Prothero; Werdelin and others)

In the fossil record, five to ten million years separate the last nimravid and the first barbourofelid. (Antón)

Is this nimravid closer to modern dogs or cats? (Image: Charles R. Knight via Wikimedia, public domain)

That’s the last nimravid.  No one knows how or when the first nimravids appeared.

Their oldest fossils go back at least thirty-five million years, but according to some research, the group may be at least fifteen million years older than that. (Averianov and others; Peigné)

That was so early in carnivore evolution that some paleontologists can link nimravid bony structures to dogs, not cats! (Flynn and Galiano)

So here we are today.  It’s very cool that predators have had a feline appearance for tens of millions of years.

Which one was the biggest and baddest: true cats or one of the “false” sabertooths?

Well, each group was big and bad enough to dominate its ecosystem.  Unfortunately, scientists still know very little about the complex environments that barbourofelids and nimravids lived in.

That leaves us with just a human scale to measure these predators with – and when it comes to love and a sort of fearful fascination, Smilodon wins paws down.

How else could this happen?


Featured image: James St. John, CC BY 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.

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

Averianov, A.; Obraztsova, E.; Danilov, I.; Skutschas, P.; and Jin, J. 2016. First nimravid skull from Asia. Nature, Scientific Reports. doi:10.1038/srep25812.

Barrett, P. Z. 2016. Taxonomic and systematic revisions to the North American Nimravidae (Mammalia, Carnivora). PeerJ. 4:31658. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756750/ Last accessed August 28, 2017.

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

Flynn, J. J., and Galiano, H. 1982. Phylogeny of early Tertiary Carnivora, with a description of a new species of Protictis from the middle Eocene of northwestern Wyoming. American Museum of Natural History.

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.

Hulbert, Jr., R. C., and Valdes, N. 2015. Smilodon fatalis. Florida Museum, University of Florida. https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/species/smilodon-fatalis/ Last accessed August 28, 2017.

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.

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.

Werdelin, L. 1996. 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.; 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.

Wright, M., and Walters, S. 1980. The Book of the Cat. New York: Summit Books.



 

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