|Information in this article is non-canon|
Smilodon /ˈsmaɪlədɒn/ is an extinct genus of machairodont felid. It is perhaps the best known saber-toothed cat and lived in the Americas during the Pleistocene epoch (2.5 mya–10,000 years ago). One of the largest collections of its fossils has been obtained from the La Brea Tar Pits. Three species of the genus are known; they vary in size and build.
Overall, Smilodon was more robustly built than any modern cat, with particularly well-developed forelimbs and exceptionally long upper canines. Its jaw had a bigger gape than modern cats and its upper canines were slender and fragile, being adapted for precision killing. These attributes likely made Smilodon a specialized hunter of large herbivores, such as bison and camels.
Smilodon likely lived in closed habitats, such as forests and bush, which would have provided cover for ambushing prey. Its reliance on large animals may have been the cause of its extinction; Smilodon died out at the same time that most North and South American megafauna disappeared, about 10,000 years ago. Scientists debate over whether Smilodon had a social or a solitary lifestyle; analysis of modern predator behavior as well as of Smilodon's fossil remains could be construed to lend support to either view.
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 the subfamily Pantherinae, whereas Smilodon belongs to the subfamily Machairodontinae. The name Smilodon comes from Greek: σμίλη, (smilē), "carving knife" and ὀδoύς (odoús), "tooth" (whose stem is odont-, as seen in the genitive case form ὀδόντος, odóntos).
Smilodon was around the size of a modern lion or tiger, but was more robustly built. It had long canines, a reduced lumbar region, high scapula, short tail, and broad limbs with relatively short feet. The brain of Smilodon was relatively small compared to other cat species. In reconstructing the facial appearance of Smilodon, Miller (1969) proposed that it looked very different from a typical cat: having a lower lip line (to allow its mouth to open so wide without tearing the facial tissues), a more retracted nose and lower placed ears. However this is disputed, and Antón, et al. (1998) wrote that the facial features of Smilodon were overall not different from those of other cats.
There is some dispute over whether Smilodon was sexually dimorphic. Some studies of Smilodon fatalis fossils have found little difference between the sexes. Conversely, a 2012 study found that, while fossils of S. fatalis show less variation in size among individuals than modern Panthera, they do appear to show the same difference between the sexes in some traits.
Smilodon had shorter and more massive limbs than other felids. It had well developed flexors and extensors in its forearms, which enabled it to pull down and securely hold down large prey so it could deliver a killing bite without endangering the vulnerable elongate canines. Analysis of the cross-sections of S. fatalis humeri indicated that they were strengthened by cortical thickening to such an extent that they would have been able to sustain greater loading than those of extant big cats, or of the extinct American lion. However, the thickening of S. fatalis femurs was within the range of extant felids. The heel bone of Smilodon was fairly long which suggests it was a good jumper.
Teeth and jaws
Smilodon skull with jaws positioned to show wide gape
Smilodon is most famous for its relatively long canines, which are the longest found in the saber-toothed cats, at about 28 cm (11 in) long in the largest species Smilodon populator.Those of S. fatalis reached their full size in 18 months at a growth rate of 7 mm/month. These canine teeth were slender and had fine serrations. They were fragile and could not have bitten into bone; thus, these cats did not use their long teeth while taking down prey, due to the risk of breaking. Only when their prey was totally subdued did they use their teeth to slash the throat.
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 saber-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 the saber-toothed cats' teeth were stronger relative to the bite force than those of modern "big cats". In addition, Smilodon's gape could have reached almost 120 degrees,while that of the modern lion reaches 65 degrees. This makes the gape wide enough to allow Smilodon to grasp large prey despite the long canines.
The genus Smilodon was named and described by the Danish naturalist and palaeontologist Peter Wilhelm Lund in 1842. He found the fossils of Smilodon populator in caves near the small town of Lagoa Santa, Minas Gerais, Brazil. It is grouped with several species of saber-toothed cats in the subfamily Machairodontinae within the family Felidae. An early ancient DNA analysis suggested that Smilodon should be grouped with modern cats (subfamily Felinae) However, a 2005 study found that Smilodon belonged to a separate lineage. Another study published a year later confirmed this, showing that the Machairodontinae diverged early from the ancestors of modern cats and were not closely related to any living feline species.
The skull and mandible morphology of the earliest saber-toothed cats were similar to that of clouded leopards. The lineage further adapted to the precision killing of large animals by developing elongated canine teeth and wider gapes, in the process sacrificing high bite force. Smilodon belongs to the tribe Smilodontini, which is known as "dirk-toothed cats". These cats were defined by their long slender canines with fine serrations.
Diet and Hunting
Smilodon was an apex predator and primarily hunted large mammals like bison, camels, ground sloths, horses and mammoths. Isotopes preserved in the bones of S, fatalis in the La Brea Tar Pits reveal that ruminants like bison and camels were most commonly taken by the cats. In addition, isotopes preserved in the enamel of S. gracilis specimens from Florida show that this species feed on the pig-like Platygonus and the llama-like Hemiauchenia. Isotopic studies of dire wolf and American lion bones show an overlap with S. fatalis in prey, which suggests that they were competitors. The availability of prey in the Rancho La Brea area was likely comparable to modern East Africa.
Smilodon was likely an ambush predator that concealed itself in dense vegetation. It probably used its great upper-body strength to wrestle prey to the ground. It may have then used its long canines to deliver a deep stabbing bite or open-jawed stabbing thrust to the throat, which would generally cut through the jugular vein and/or the trachea and thus kill the prey very quickly. Alternatively, it may have used its canines to puncture the thoracic wall of its prey (a larger, easier target) with a closed-mouth stab, creating a condition of pneumothorax (collapsed lungs). By contrast, modern cats kill large prey with a suffocating bite. Another hypothesis suggests that Smilodon targeted the belly of its prey. This is disputed, however, as the curvature of their prey's belly would likely have prevented the cat from getting a good bite. Whether Smilodon generally used its canines to deliver a point-to-point bite, open-jawed stab or closed-jawed stab is unclear. Smilodon probably avoided eating bone and would have left enough food for scavengers. Smilodon itself may have scavenged dire wolf kills.
Smilodons in Land Before Time
There were some in The Land Before Time XVIII: Journey Under the Great Valley . They were near the Fire Rock. They are classified as "Sharptooth Tickly Fuzzies " by Thicknose and others.