Smilodon: The Sabre-Tooth (not a) Tiger

Smilodon looking over his kingdom
Image Credit: Charles R Knight, http://www.charlesrknight.com/dinosaur-artist-charles-r-knight/Knight%20article.pdf

Right, I’m going to start off by clearing up a common misconception. Despite often being called it in popular media Smilodon was NOT a Sabre-Toothed Tiger, or related to tigers at all! It was a Sabre-Tooth Cat (or Machairodontinae if you want to get technical). Also, the term “Sabre-Tooth Cat” refers to the family that Smilodon is a part of rather than just Smilodon itself. Other examples of Sabre-Tooth Cats include; Dinofelis, which lived across Africa, Eurasia and North America during the Pliocene to the Early Pleistocene (5.5-1.5 million years ago) and has a reputation for being a hunter of Australopithecus and other early human ancestors (which it may or may not have done). Another example is Homotherium, a smaller Sabre-Tooth Cat species which lived around the same place and time as Smilodon.

With that out of the way, let’s find out more about this large and rather striking extinct kitty.

To start with, the first piece of anatomy that everyone notices when looking at Smilodon is its large sabres (which could measure up to 28cm long – almost as long as a school ruler!). Contrary to popular belief Sabre-Tooth Cats like Smilodon were not the first animals to evolve sabre teeth. That title instead goes to animals like the Gorgonopsids, a group of “mammal-like reptiles” that lived in the Late Permian period around 265-250 million years ago. They, and other “mammal-like reptiles” are a fascinating group of animals in their own right which I’m sure I’ll tackle in a later blog. While the sabres in Smilodon look very formidable they were actually surprisingly fragile, and could break easily if used for usual ripping and slashing attacks. Smilodon also had a relatively weak bite, and needed to open its mouth very wide in order to extend the sabres out fully. As a result it is thought that the sabres were used for careful, quick surgical bites to the prey’s neck in order to puncture the neck and ensure a quick end without too much struggle. The iconic positioning of these sabre-teeth is that they’re exposed on the outside. While this continues to be scientific consensus there have been suggestions that Smilodon and other sabre-tooth cats may have had fleshy lips covering them instead.

A reconstructed skeleton of Smilodon fatalis from the Sternberg Museum of Natural History in Hays, Kansas, USA. As you see the sabre-teeth are certainly eye-catching!
Image Credit: James St John, https://www.flickr.com/photos/jsjgeology/15420386216

There are other parts of Smilodons anatomy that also set it apart from modern day big cats. It was larger and more heavily built than a modern lion or tiger, measuring up to 1.5 metres long, a metre high and weighing up to 400 kilograms. Smilodon also possessed thick front leg bones with big muscle attachments. This suggests that Smilodon would not have been a pursuit hunter, but instead an ambush predator, stalking its prey, getting close and then leaping out and pinning them down using their powerful front legs, before then employing the sabres. In terms of behaviour it was a matter of debate as to whether Smilodon lived in prides (like lions) or were solitary like tigers, with reconstructions, paleoart and documentaries switching between the two. However some fossil Smilodon show previous serious injury and not only managed to recover but live to an old age. Also a joint study in 2008 by the Zoological Society of London and the University of California, assessed the large number of Smilodon remains found at Rancho La Brea Tar Pits who had turned up at the tar pits in response to prey distress calls. They compared these with the numbers of modern African predators that turned up to similar distress calls at similar traps. The results showed that the number of Smilodon found compared well to the numbers of pack hunting animals, such as lions and hyenas. Both of these observations indicate that these sabre-toothed cats lived in packs. (On a side note; Rancho La Brea is in my top 5 places to visit in the world!)

Smilodon fossils have been found across the Americas, having first evolved in North America before migrating to South America via the newly formed Isthmus of Panama land bridge. The first fossils, being of the South American species Smilodon populator, were discovered by Lund in Brazil in 1840. Further species discovered, all mostly based in North America, include; Smilodon fatalis (discovered by Leidy in 1869) and Smilodon gracilis (discovered in 1880 by the legendary Edward Drinker Cope of dinosaur fossil fame). Of these species Smilodon populator was both the youngest, evolving only 1 million years ago, and the largest.

A size comparison between 3 different Smilodon species and an average human. Smilodon populator of South America was the largest, followed by the North American Smilodon fatalis and Smilodon gracilis.
Image Credit: Aledgn, https://commons.m.wikimedia.org/wiki/File:Wiki_Smilodon_Size.png

Such a beautiful cat would be a sight to witness across the American plains. Sadly, like the rest of the megafauna that lived alongside them, they died out during the last Ice Age around 10,000 years ago. A few reasons have been suggested for this; competition with humans for prey being one of them. However it is likely that a changing climate, resulting in habitat reduction, and the loss of the large megafauna that Smilodon preyed on (which could have partly been a result of human hunting) were the main reasons. With large prey gone and with Smilodon not having the endurance to hunt the smaller, swifter mammal herbivores that remained, their numbers dwindled.

Still, Smilodon has gone down in history as one of the most striking extinct animals yet described. Its sabres have repeatedly captured the imagination of generations of people in museums and in popular media. Personally I’m sure of two things about Smilodon:

1. If I had to pick a fossil skull to own, it would be one of these sabre tooth cats, and

2. If one of them could speak it would have the voice of Denis Leary!

EDIT: A small addition to this blog. As well as being found in the USA Smilodon fatalis has also recently been discovered to live as far north as Canada, with the paper describing the new Canadian fossils (Reynolds, Seymour & Evans 2019) only published in January 2019.

References/Further Reading

Carbone et. al. 2008 paper on pack hunting behaviour in Smilodon

Carbone, Chris, Maddox, Tom, Funston, Paul J, et. al., (2008), Parallels between playbacks and Pleistocene tar seeps suggest sociality in an extinct sabretooth cat, Smilodon, Biol. Lett.5, 81–85, https://doi.org/10.1098/rsbl.2008.0526

An interesting blog by Mark Witton, published on his blog site, on exposed teeth in Paleontological reconstructions. Smilodon is one of the animals he talks about.

Witton, Mark, “Exposed teeth in dinosaurs, sabre-tooths and everything else: thoughts for artists”, markwitton.com/blog, Oct. 9, 2016, markwitton-com.blogspot.com/2016/10/exposed-teeth-in-dinosaurs-sabre-tooths.html

Christiansen & Harris 2005 paper, published in Journal of Morphology, on body size estimates of three Smilodon species

Christiansen, P. and Harris, J.M. (2005), Body size of Smilodon (Mammalia: Felidae). J. Morphol., 266: 369-384. doi:10.1002/jmor.10384

Reynolds, Seymour & Evans paper on the Canadian Smilodon fatalis fossils (For the EDIT).

Reynolds, A. R., et al. (2019). “Late Pleistocene records of felids from Medicine Hat, Alberta, including the first Canadian record of the sabre-toothed cat Smilodon fatalis.” Canadian Journal of Earth Sciences 56(10): 1052-1060.

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