Smilodon opening wide. The cat could open its jaws to an incredible 120º (Art by Tabitha Paterson)

Smilodon is the genus of extinct sabretooth that everyone knows. Stocky, hugely muscled, with canines that protrude far below the jaw, it is the archetypal Pleistocene predator. It was a member of the machairodontinae, an extinct subfamily of the Felidae (all modern cats are members of the subfamily felinae), which split from the ancestors of our furry house-pets way back in the Miocene. Interestingly enough, it was almost as different from Homotherium as it was from lions, tigers, and kin. The scimitar-cat split very early on from Smilodon and its relatives. In fact, there are three species of Smilodon known to science. The earliest, Smilodon gracilis, lived in North America during the late Pliocene to middle Pleistocene, and was probably a direct ancestor of the two later species, Smilodon fatalis (found in North America and western South America) and Smilodon populator (found in eastern South America). Smilodon populator was probably the largest sabretooth that ever lived- average individuals easily weighing over 250kg! This enormous cat has been found at many sites in South America and even made it down to Tierra del Fuego.

The size of Smilodon compared with Rey shows just how big this cat would have been. (Image by Jan Freedman)

The most distinct feature of Smilodon is obviously its enormous canines. Measuring up to 11 inches long with enormous roots to keep them anchored within the skull, the teeth grew at a much faster rate than in modern cats. Smilodon kittens started off with milk canines, and in a similar fashion to modern cats, the adult teeth actually grew in alongside the deciduous teeth- meaning that some young sabrecats actually had four sabres in their mouth for a short period of time. This must have looked incredible, as we know that Smilodon was a very “gummy” cat. The gums likely extended quite far down the canine, and had a unique, stepped, profile that probably allowed the cat to know the penetrance of the teeth during the killing bite, giving greater control of the placement.

The canines of Smilodon were pretty delicate and prone to breakage (due to their thin cross-section). Many individuals from the famous tarpit site of Rancho la Brea even show evidence of living for years after the loss of one (or both) sabres, shown by the reseach of the great TrowelBlazer, Blaire Van Valkenburgh. This observation leads directly on to one of the most interesting questions in cat palaeontology- was Smilodon social? We know of individuals who survived long periods with broken sabres (the broken ends became polished through use by the living animal), and the la Brea skeletons also show examples of animals with massively debilitating skeletal problems (crippling arthritis, badly healed fractures), so could these cats have had a group structure that allowed incapacitated members to feed? There is evidence both for and against this idea. Positive evidence includes comparisons to what happens in modern ecosystems when recordings are played of a herbivore in distress (as would have happened at la Brea when animals got stuck in the tar)- social carnivores show up more often than asocial carnivores. The numbers of Smilodon at la Brea are very high, and only comparable to another presumably social predator, the dire wolf (Canis dirus). Against the sociality argument is the fact that modern felids are almost exclusively solitary (with the exception of the lion), and the lion species found at la Brea (Panthera leo atrox) is present at a much lower frequency than Smilodon. Felids also have very high metabolic rates and a fast healing process, which means that wounds and breaks tend to heal faster than we expect. What would be a debilitating wound in some mammal species may have not been so for a felid.

So there you have it. Smilodon: the sometimes four sabred, gummy, panamerican maybe social sabretooth (not quite a) cat.

And as a postscript: did you know that that Smilodon had a recurring role in the series Friends? Ross Geller, despite supposedly being a dinosaur expert, had a replica skull of Smilodon fatalis on the bookshelf in his apartment. Also in “the one with Ross’ library book” when Ross is patrolling the library section to prevent students from using the area to make out, he sarcastically comments “Oh-oh, you’re fellow scholars. What exactly were you looking for, hmm? Perhaps, Dr. Chester Stock’s musings on the Smilodon californicus?” This is a real book, written in conjunction with JC Merriam (who gets a shoutout later in the scene), and perhaps the definitive work on Smilodon from Rancho la Brea.

Written by Ross Barnett (@DeepFriedDNA)

Art by Tabitha Paterson (@TabithaPaterson)

Further reading:

Barnett, R., et al. (2005), ‘Evolution of the extinct sabretooths and American cheetahlike cat’, Current Biology, 15 (15), R589-R90. [Full article]

Berta, A. (1987), ‘The sabercat Smilodon gracilis from Florida and a discussion of its relationships (Mammalia, Felidae, Smilodntini)’, Bulletin of the Florida State Museum of Bioogical Sciences, 31 (1), 1-67. [Full article]

Carbone, C., et al. (2009), ‘Parallels between playbacks and Pleistocene tar seeps suggest sociality in an extinct sabretooth cat, Smilodon’, Biology Letters, 5, 81-85. [Full article]

Christiansen, P. and Harris, J. M. (2005), ‘Body Size of Smilodon (Mammalia: Felidae)’, Journal of Morphology, 266, 369-84. [Abstract only]

Feranec, R. S. (2004), ‘Isotopic evidence of saber-tooth development, growth rate, and diet from the adult canine of Smilodon fatalis from Rancho La Brea’, Palaeogeography, Palaeoclimatology, Palaeoecology, 206 (3-4), 303-10. [Full article]

Merriam, J. C. and Stock, C. (1932), The Felidae of Rancho La Brea (Carnegie Institute of Washington Publications). [Book]

Prevosti, F. J., Martin, F. M., and Massone, M. (2013), ‘First record of Smilodon Lund (Felidae, Machairodontinae) in Tierra del Fuego Island (Chile)’, Ameghiniana, 50 (6), 605-10. [Full article]

Tejada-Flores, A. E. and Shaw, C. A. (1984), ‘Tooth replacement and skull growth in Smilodon from Rancho la Brea’, Journal of Vertebrate Paleontology, 4 (1), 114-21. [Abstract only]

van Valkenburgh, B. and Hertel, F. (1993), ‘Tough Times at La Brea: Tooth Breakage in Large Carnivores of the Late Pleistocene’, Science, 261, 456-59. [Full article]