Smilodon ( /ˈsmaɪlədɒn/), often called a saber-toothed cat or incorrectly a saber-toothed tiger, is an extinct genus of machairodonts. This saber-toothed cat was endemic to North and South America, living during the Pleistocene epoch (2.5 mya—10,000 years ago).
The nickname "saber-tooth" refers to the extreme length of their maxillary canines. Despite the colloquial name "saber-toothed tiger", Smilodon is not closely related to the tiger (or any other living felid); the latter belongs to subfamily Pantherinae, whereas Smilodon belongs to subfamily Machairodontinae. The name Smilodon comes from Greek: σμίλη, (smilē), "carving knife" + ὀδoύς (odoús), "tooth", or in the genitive: ὀδoύς, ὀδόντος, odóntosThe genus Smilodon was described by the Danish naturalist and palaeontologist 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. Genetic evidence suggests the members of the genus diverged from the main lineage of modern cats (subfamily Felinae) around 14-18 million years ago.
Smilodon gracilis, 2.5 million-500,000 years ago; the smallest and earliest species, estimated at 55 to 100 kg (120 to 220 lb) in weight 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. Matching the largest living cat, the Siberian tiger in size, it ranged from 160 to 280 kg (350 to 620 lb).[7] Sometimes two additional species are recognized, Smilodon californicus and Smilodon floridanus, but usually they are considered to be subspecies of Smilodon fatalis.
Smilodon populator, 1 million-10,000 years ago; occurred in the eastern parts of South America and it was perhaps the largest known felid with a body mass range of 220 to 360 kg (490 to 790 lb) possessing a massive chest and front legs, It was more than 1.40 m (55 in) high at the shoulder, 2.6 m (100 in) long on average and had a 30 cm (12 in) tail. Its upper canines reached 30 cm (12 in) and protruded up to 17 cm (6.7 in) out of the upper jaw.
The species of Smilodon were among the largest felids ever to live; the heaviest specimens of the massively built carnivore S. populator may have exceeded 400 kg (880 lb).
A fully-grown Smilodon weighed approximately 55 to 360 kg (120 to 790 lb), depending on species. It had a short tail, powerful legs, muscular neck and long canines. Smilodon was more robustly built than any modern cat, comparable to a bear. The lumbar region of the back was proportionally short, and the lower limbs were shortened relative to the upper limbs in comparison with modern pantherine cats, suggesting that Smilodon was not built for speed.
The largest species, the South American S. populator, had higher shoulders than hips and a back that sloped downwards, superficially recalling the shape of a hyena, in contrast to the level-backed appearance of S. fatalis, which was more like that of modern cats. However, while its front limbs were relatively long, their proportions were extremely robust and the forearm was shorter relative to the upper arm bone than in modern big cats, and proportionally even shorter than in S. fatalis. This indicates these front limbs were designed for power rather than fast running, and that S. populator would have had immense strength in its forequarters.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 saber-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.
Restoration by Charles R. Knight
Modern big cats kill mainly by crushing the windpipe of their victims, which may take a few minutes. Smilodon’s jaw muscles were probably too weak for this and its long canines and fragile skull would have been vulnerable to snapping in a prolonged struggle or when biting a running prey. Research in 2007 concluded that Smilodon most likely used its great upper-body strength to wrestle prey to the ground, where its long canines could deliver a deep stabbing bite to the throat which would generally cut through the jugular vein and/or the trachea and thus kill the prey very quickly. The leaders of this study also commented to scientific journalists that this technique may have made Smilodon a more efficient killer of large prey than modern lions or tigers, but also made it more dependent on the supply of large animals. This highly specialized hunting style may have contributed to its extinction, as Smilodon’s cumbersome build and over-sized canines would have made it less efficient at killing smaller, faster prey if the ecosystem changed for any reason.A later study concurred, finding that the forelimbs of Smilodon, more than those of any modern felid, were capable of minimizing the struggles of prey and positioning them for a quick kill with the predator's canines without them fracturing.
Smilodon became extinct at the end of the Pleistocene around 10,000 BC, a time which saw the extinction of many other large herbivorous and carnivorous mammals.
Prehistoric humans, who reached North America at the same time and are known to have hunted many of the species that disappeared, are often viewed as responsible for this extinction wave. Others have suggested that the end of the ice age caused the extinction. As the ice sheets retreated there would have been changing vegetation patterns. Grasslands expanded. The summers became more extreme and parts of North America began to dry out. However, this hypothesis does not explain why Smilodon and its ancestors as well as other megafaunal species successfully survived many previous interglacials, and then fairly suddenly died out over the entire contiguous land area of North and South America.
