The nickname "sabre-tooth" refers to the extreme length of their maxillary canines. Despite the colloquial name "sabre-toothed tiger", Smilodon is not a tiger; the latter belongs to subfamily Pantherinae, whereas Smilodon belongs to subfamily Machairodontinae. The name Smilodon comes from Greek: σμίλη, smilē, "chisel" and Greek ὀ δoύς (ho doús), "the tooth", Genitive: δoύς, δόντος,dóntos.
The genus Smilodon was described by the Danish naturalist and paleontologist Peter Wilhelm Lund in 1841. He found the fossils of Smilodon populator in caves near the small town of Lagoa Santa, in the state of Minas Gerais, Brazil.
A number of Smilodon species have been described, but today usually only three are recognized.
- Smilodon gracilis, 2.5 million-500,000 years ago; the smallest and earliest species (estimated to have been only 55 to 100 kg (120 to 220 lb)) was the successor of Megantereon in North America, from which it probably evolved. The other Smilodon species probably derived from this species.
- Smilodon fatalis, 1.6 million-10,000 years ago, replaced Smilodon gracilis in North America and invaded western South America as part of the Great American Interchange. In size it was between Smilodon gracilis and Smilodon populator, and about the same as the largest surviving cat, the Siberian Tiger. This species was about 1 m high at the shoulder and is estimated to have ranged from 160 to 280 kg (350 to 620 lb). Sometimes two additional species are recognized, Smilodon californicus and Smilodon floridanus, but usually they are considered to be subspecies of Smilodon fatalis.
- Smilodon populator ("the devastating Smilodon"), 1 million-10,000 years ago; occurred in the eastern parts of South America and was the largest species of all machairodonts. It was much larger than its cousins, S. fatalis and S. gracilis, possessing a massive chest and front legs, and is the largest known variety of sabre-toothed cat. It was more than 1.22 m (48 in) high at the shoulder, 2.6 m (100 in) long on average and had a 30 cm (12 in) tail. With an estimated weight of 360 to 470 kg (790 to 1,000 lb), it was among the heaviest known felids. Its upper canines reached 30 cm (12 in) and protruded up to 17 cm (6.7 in) out of the upper jaw. Genetic evidence suggests that Smilodon populator and other members of the genus diverged from the main lineage of modern cats (subfamily Felinae) around 14-18 million years ago.
Smilodon probably preyed on a wide variety of large game including bison, tapirs, deer, American camels, horses and ground sloths. As it is known for the sabre-toothed cat Homotherium, Smilodon might have also killed juvenile mastodons and mammoths. Smilodon may also have attacked prehistoric humans, although this is not known for certain. The La Brea tar pits in California trapped hundreds of Smilodon in the tar, possibly as they tried to feed on mammoths already trapped. The Natural History Museum of Los Angeles County has many of their complete skeletons.
Research upon which African carnivores respond to playback of animals in distress has been used to analyses the finds of animal species and their numbers at the La Brea tar pits. Such playbacks find animal distress calls such as would come from an animal trapped in the tar pit would attract pack hunters such as lions and spotted hyenas, not lone hunters. Given the carnivores found at tar pits were predominately Smilodon and the social dire wolf, this suggests that the former like the latter was also a social animal. One expert, who found the study convincing, further speculated that if that was the case, then Smilodon's exaggerated canine teeth might have been used more for social or sexual signaling than hunting. [Full citation needed] However, the lack of sexual dimorphism in the canine teeth makes this unlikely.
Smilodon is most famous for its relatively long canines, which are the longest found in the sabre-toothed cats, at about 28 cm (11 in) long in the largest species Smilodon populator.
They did not use their long teeth particularly for hunting in risk of breaking them; only when the prey is totally subdued did they use their teeth to simultaneously sever the blood supply and strangle the wind pipe, instantly killing their prey. The 20 cm sabres were fragile and could not have bitten into bone.[citation needed]
Despite being more powerfully built than other large cats, Smilodon actually had a weaker bite. Modern big cats have more pronounced zygomatic arches, while Smilodon had smaller zygomatic arches which restricted the thickness and therefore power of the temporalis muscles, and thus reduced Smilodon’s bite force. Analysis of its narrow jaws indicates that it could produce a bite only a third as strong as that of a lion. There seems to a be a general rule that the sabre-toothed cats with the largest canines had proportionally weaker bites. However, analyses of canine bending strength (the ability of the canine teeth to resist bending forces without breaking) and bite forces indicate that sabre-toothed cats' teeth were stronger relative to the bite force than those of modern "big cats". In addition, Smilodon could open its jaws 120 degrees, whereas the lion's gape is limited to 60 degrees.
It has been suggested that Smilodon's smaller temporalis muscles (controlling much of the bite force) were not used in the killing of prey; rather, Smilodon stretched its jaws around the throat and pressed its canines into the prey with the use of its immense neck and forelimb muscles. The penetration was the result of the neck flexors instead of the jaw muscles, according to this hypothesis.
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