Name: Smilodon fatalis
Age: Pleistocene – 700,000 to 11,000 years ago approx.
Size: 1m tall at the shoulder approx.
Weight: Up to 300 kg
Location: North and South America
Arguably one of the most famous of all extinct mammals, along with the Woolly Mammoth and Woolly Rhino, is the fearsome Smilodon. Known for its elongated canine teeth, it is often referred to as a sabre-toothed tiger, yet it is not actually a tiger at all. It belongs to a separate subfamily of cats called Machairodontinae, a group to which no living cats belong. Smilodon fatalis was first discovered in 1868 by Joseph Leidy, and is one of three species of Smilodon; the others being S.gracilis (the oldest known species), and S.populator (the largest known species).
Smilodon was originally the apex predator of North America. However, following the formation of the Panamanian Isthmus, these big cats moved into South America. In this new territory they soon displaced ‘terror birds’ (phorusrhacids) as the top predators. The species S. gracilis is thought to have made this continental transition, and it is believed that one of the other two species may, in fact, have evolved in South America, but this is unclear at the present time. Smilodon may have sometimes been hostile towards each other, as evident by the presence of injuries on one skull that are similar in size and shape to Smilodon canines, so most likely represent where one of these cats attacked another.
The sabre-shaped teeth of Smilodon are around 150 mm long and curve backwards. It is thought the animal could have killed in one of two ways. It may have used its short, stocky front legs and powerful shoulder muscles to pin its prey to the ground before using these sabre-teeth to puncture the windpipe and sever arteries in the neck of its helpless victim. However, some disagree and believe that the teeth were used to disembowel the prey animal (cut open its belly). Recent research analysing the forces involved in S. fatalis’ bite agrees with the former rather than the latter, and suggests that the predatory cat was most likely slashing the throat of prey animals. Smilodon had to be cautious when hunting, fighting and eating, as the sabre-teeth were incredibly delicate, and likely to break under significant force. This likely made the genus wasteful when eating, encouraging scavengers to follow Smilodon in order to gain a piece of the kill.
Whilst Smilodon is the animal most well known for having sabre-teeth, this adaptation has evolved multiple times throughout history. Many different families of mammals have evolved these teeth, however, it is unknown if they all used their sabres in the same way. A marsupial named Thylacosmilus is a prime example, which also had a projection of the lower jaw that followed the sabres downwards (the function of which is unknown).
Smilodon hunted a majority of herbivores in their territories, such as bison, Toxodon, or Macrauchenia. It is likely that once these large prey animals began to die out, so did Smilodon. These cats were super specialised predators, evolved near-perfectly to ambush and overpower equally large prey, and once these prey animals became extinct, it was unlikely that Smilodon could capture faster animals like deer or antelope. Humans have also been indirectly blamed for the extinction of the sabre-toothed cats, outcompeting them by hunting Smilodon prey animals as their own food source.
Smilodon skull courtesy of Stephan Lautenschlager.
Information References and Further Sources:
 Anyonge, W. (1996). Microwear on Canines and Killing Behavior in Large Carnivores: Saber Function in Smilodon fatalis, Journal of Mammalogy, 77 (4), pp 1059-1067. doi: https://doi.org/10.2307/1382786. Available at: https://tinyurl.com/y44rtfwq. Accessed 7th March 2019.
 Benton, M. J. (2014). Vertebrate Palaeontology. 4th ed. Oxford: Wiley-Blackwell. pp 380.
 Chimento, N. R., Agnolin, F. L., Soibelzon, L., Ochoa, J. G., and Buide, V. (2019). Evidence of intraspecific agonistic interactions in Smilodon populator (Carnivora, Felidae), Competes Rendus Palevol. doi: https://doi.org/10.1016/j.crpv.2019.02.006. Available at: https://www.sciencedirect.com/science/article/pii/S1631068319300612. Accessed 17th May 2019.
 Figueirido, B., Lautenschlager, S., Pérez-Ramos, A., and Van Valkenburgh, B. (2018). Distinct Predatory Behaviours in Scimitar- and Dirk-Toothed Sabertooth Cats, Current Biology, 28(20), pp 3260-3266.E3. doi: https://doi.org/10.1016/j.cub.2018.08.012. Available at: https://www.cell.com/current-biology/fulltext/S0960-9822(18)31057-1. Accessed 16th May 2019.
 Hulbert Jr, R. C., and Valdes, N. (2015). ‘Smilodon fatalis’, Florida Museum, 11th March. Available at: https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/species/smilodon-fatalis. Accessed 7th March 2019.