Instruct: Given a question, retrieve documents that can help answer the question.
Query: When was the Smilodon discovered?
Fossils of Smilodon were discovered in North America from the second half of the 19th century onwards.[1] In 1869, American paleontologist Joseph Leidy described a maxilla fragment with a molar, which had been discovered in a petroleum bed in Hardin County, Texas. He referred the specimen to the genus Felis (which was then used for most cats, extant as well as extinct) but found it distinct enough to be part of its own subgenus, as F. (Trucifelis) fatalis.[5] The species name means "fate" or "destiny", but it is thought Leidy intended it to mean "fatal".[6] In an 1880 article about extinct American cats, American paleontologist Edward Drinker Cope pointed out that the F.fatalis molar was identical to that of Smilodon, and he proposed the new combination S.fatalis.[7] Most North American finds were scanty until excavations began in the La Brea Tar Pits in Los Angeles, where hundreds of individuals of S.fatalis have been found since 1875.[1] S.fatalis has junior synonyms such as S.mercerii, S.floridanus, and S.californicus.[4] American paleontologist Annalisa Berta considered the holotype of S.fatalis too incomplete to be an adequate type specimen, and the species has at times been proposed to be a junior synonym of S.populator.[3] Swedish paleontologists Björn Kurtén and Lars Werdelin supported the distinctness of the two species in 1990.[8]
Many Smilodon specimens have been excavated from asphalt seeps that acted as natural carnivore traps. Animals were accidentally trapped in the seeps and became bait for predators that came to scavenge, but these were then trapped themselves. The best-known of such traps are at La Brea in Los Angeles, which have produced over 166,000 Smilodon fatalis specimens[59] that form the largest collection in the world. The sediments of the pits there were accumulated 40,000 to 10,000 years ago, in the Late Pleistocene. Though the trapped animals were buried quickly, predators often managed to remove limb bones from them, but they were themselves often trapped and then scavenged by other predators; 90% of the excavated bones belonged to predators.[60]
Despite the colloquial name "saber-toothed tiger", Smilodon is not closely related to the modern tiger (which belongs in the subfamily Pantherinae), or any other extant felid.[19] A 1992 ancient DNA analysis suggested that Smilodon should be grouped with modern cats (subfamilies Felinae and Pantherinae).[20] A 2005 study found that Smilodon belonged to a separate lineage.[21] A study published in 2006 confirmed this, showing that the Machairodontinae diverged early from the ancestors of modern cats and were not closely related to any living species.[22] The following cladogram based on fossils and DNA analysis shows the placement of Smilodon among extinct and extant felids, after Rincón and colleagues, 2011:[16]
The brain of Smilodon had sulcal patterns similar to modern cats, which suggests an increased complexity of the regions that control the sense of hearing, sight, and coordination of the limbs. Felid saber-tooths in general had relatively small eyes that were not as forward-facing as those of modern cats, which have good binocular vision to help them move in trees.[45] Smilodon was likely an ambush predator that concealed itself in dense vegetation, as its limb proportions were similar to modern forest dwelling cats,[46] and its short tail would not have helped it balance while running.[47] Unlike its ancestor Megantereon, which was at least partially scansorial and therefore able to climb trees, Smilodon was probably completely terrestrial due to its greater weight and lack of climbing adaptations.[48] The heel bone of Smilodon was fairly long, which suggests it was a good jumper.[23] Its well-developed flexor and extensor muscles in its forearms probably enabled it to pull down, and securely hold down, large prey. 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. The thickening of S.fatalis femurs was within the range of extant felids.[49] Its canines were fragile and could not have bitten into bone; due to the risk of breaking, these cats had to subdue and restrain their prey with their powerful forelimbs before they could use their canine teeth, and likely used quick slashing or stabbing bites rather than the slow, suffocating bites typically used by modern cats.[49] On rare occasions, as evidenced by fossils, Smilodon was willing to risk biting into bone with its canines. This may have been focused more towards competition such as other Smilodon or potential threats such as other carnivores than on prey.[48]
Regions Bank and UBS maintained a display in their first floor lobby that included bones from the "Smilodon" and other faunal material from the site. In 2016, the display was moved to Bridgestone Arena. "Smilodon" remains on display include portions of the lower jaw and molars, vertebral column, ribs, humerus, metacarpals, and metatarsals. A replica of a "Smilodon" skull from the La Brea Tar Pits serves as the centerpiece of the display. The Smilodon upper canine that led to the site discovery in 1971 is not on display, and is apparently no longer in the collection. Conventional wisdom among bank and facility management personnel is that the canine is now in the collection of the Smithsonian; however, that institution holds no record of the artifact.
A Smilodon appeared for the first time in episode 2.3, where it is responsible for a number of deaths at a theme park. When the team hear of this, Connor wonders why the Anomaly detector he has recently built didn't detect an Anomaly in the theme park; it is later revealed that the Smilodon had came through its Anomaly as a cub years before the events of the episode, and had been kept as a pet by a ranger called Valerie who had lost control of it as it became more aggressive and turned man-eater upon maturing; she was certain that her pet would never hurt her after all she had done for it over the years, but was proved wrong when it later killed her. At the end of the episode, Oliver claims the cat is dead, killed by an apparent heart attack after being tranquillised; Nick questions how this could have happened when it was a perfectly healthy animal. Oliver is revealed to have been lying in episode 2.7, where it is revealed he has built up his own army of creatures that his men have kidnapped from their own time and that the Smilodon is now one of the creatures in his army. He tries to use it to kill Connor, Abby, Jenny and Caroline, but Nick tricks him into opening the prison and the Smilodon escapes. It is later lured back to the prison along with the other creatures by Nick, Helen and Stephen; it then participates in killing Stephen. It is assumed that the creatures turned on and killed each other after killing Stephen and that the Smilodon, and the rest of Oliver's creatures, are all dead.
Smilodon lived during the Pleistocene epoch (2.5 mya–10,000 years ago), and was perhaps the most recent of the saber-toothed cats.[23] Smilodon probably lived in a closed habitat such as forest or bush.[77] Fossils of the genus have been found throughout the Americas.[3] In North America, the varied habitat supported other saber-toothed cats in addition to Smilodon, such as Homotherium and Xenosmilus; the habitat here varied from subtropical forests and savannah in the south, to treeless mammoth steppes in the north. Smilodon inhabited the temperate latitudes of North America, where the mosaic vegetation of woods, shrubs, and grasses in the southwest supported large herbivores such as horses, bison, antelope, deer, camels, mammoths, mastodons, and ground sloths. Other large carnivores included dire wolves, short-faced bear (Arctodus simus) and the American lion.[13][60][78] Due to competition from larger carnivores in North America, S.fatalis was perhaps not able to attain the same size as S.populator. The similar sizes of S.fatalis and the American lion suggests niche overlap and direct competition between these species, and they appear to have fed on similarly sized prey.[79]
Miller also suggested a pug-like nose. Aside from the pug and similar dogs, no modern carnivore exhibits a pug nose due to it being an unnaturally created trait originating from selective breeding. The relatively low distribution of the pug nose has resulted in it being generally ignored.[32] Miller's rationale is based on the retraction of Smilodon nasal bones. Criticism of Miller's theory compares the nasal bones of lions and tigers. Lions, when compared to tigers, also have strongly retracted nasal bones, but a lion's rhinarium, or external nose, is no more retracted than the tiger's. Thus, the pug nose of Smilodon proposed by Miller has little evidence in the physical structures of comparable animals. According to Antón, García-Perea and Turner (1998), the nostrils of living felids always extend to a similar position, independently of the length of the nasal bones, which in Smilodon falls within the range observed in modern species.[31]
 is Ryubee's beloved pet blue British Shorthair, named by his son Raito (Philip). Despite being a cat, the Smilodon Memory can transform Mick into the humanoid that can discharge electricity and move at blinding speeds, fast enough to evade the homing shots of Kamen Rider Double LunaTrigger and outmaneuver Kamen Rider Accel Trial. He appears to be more intelligent than the average house cat, in that he appears to know that he is able to transform into the Smilodon Dopant and he knows how to transform back into a house cat at will. He is often utilized by the Sonozaki Family to deal with matters outside their estate, such as hunting down Philip and traitors, as well as bodyguard and spy. Mick also appears to favor Wakana over the other members of the family though will faithfully follow Ryubee's orders. While targeting Kyoko, the Smilodon Dopant defeats Accel Trial before Double CycloneMetal catches the cat off guard before destroying his Gaia Driver and Smilodon Memory with the Metal Stag Break Maximum Drive. After Ryubee's death, Mick is brought to live at the Narumi Detective Agency.
Felidae Proailurus Pseudaelurus Panthera (tigers, lions, jaguars, and leopards) Caracal Leopardus (ocelot and relatives) Felis (domestic cats and relatives) Herpailurus (jaguarundi) Miracinonyx (American cheetah) Puma (cougar) Dinofelis Nimravides Machairodus Homotherium Xenosmilus Paramachairodus Megantereon Smilodon gracilis Smilodon populator Smilodon fatalis
S.populator was very successful, while Homotherium never became widespread in South America. The extinction of the thylacosmilids has been attributed to competition with Smilodon, but this is probably incorrect, as they seem to have disappeared before the arrival of the large cats. The phorusrhacid "terror birds" may have dominated the large predator niche in South America until Smilodon arrived.[13] S. populator may have been able to reach larger size than S. fatalis due to a lack of competition in Pleistocene South America; S. populator arrived after the extinction of Arctotherium angustidens, one of the largest carnivores ever, and could therefore assume the niche of mega-carnivore.[79] S. populator preferred large prey from open habitats such as grassland and plains, based on evidence gathered from isotope ratios that determined the animal's diet. In this way, the South American Smilodon species was probably similar to the modern lion. S. populator probably competed with the canid Protocyon there, but not with the jaguar, which fed primarily on smaller prey.[81][82]
The latest Smilodon fatalis specimen recovered from the Rancho La Brea tar pits has been dated to 13,025 years ago.[85] The latest Smilodon populator remains found in the cave of Cueva del Medio, near the town of Soria, northeast Última Esperanza Province, Magallanes Region in southern-most Chile, and have been dated 10,935–11,209 years ago.[86]
Smilodon started developing its adult saber-teeth when the animal turned one-and-a-half years of age, shortly after the completion of the eruption of the cat's baby teeth. Both baby and adult canines would be present side by side in the mouth for an 11-month period, and the muscles used in making the powerful bite were developed at about one-and-a-half years old as well, eight months earlier than in a modern lion. After Smilodon turned around 20 months of age, the infant teeth were shed while the adult canines grew at an average growth rate of 7mm (0.3in) per month during a 12-month period. They reached their full size at around 3 years of age, later than for modern species of big cat. Juvenile and adolescent Smilodon specimens are extremely rare at Rancho La Brea, where the study was performed, indicating that they remained hidden or at denning sites during hunts, and depended on parental care while their canines were developing.[70][71][72]
When the mammoths finally come, D'Leh and the other men of the tribe hunt them under Tic'Tic's leadership, and D'Leh manages to kill one of them by causing the animal into skewering itself on his spear, inadvertently winning the White Spear. He also wins Evolet in marriage. However, consumed by the guilt that he did not earn the White Spear fairly, after speaking with Tic'Tic, he gives up the White Spear and by effect, forfeits his marriage to Evolet. The next day, horse-raiders attack the camp, enslaving Evolet and several others and killing many of the tribe. D'Leh, Tic'Tic, Ka'Ren and the young boy Baku set out to rescue Evolet and their fellow Yagahl, but she is recaptured with Ka'Ren and Baku during an attack on the slavers by Terror Birds. Tic'Tic is wounded by the predators during the battle. D'Leh and the injured Tic'Tic continue on. When D'Leh is out hunting, he falls into a pit. When he wakes from the fall, he suddenly finds and rescues a "Smilodon" trapped in the pit under fallen debris and then escapes himself. After Tic'Tic recovers, they make their way to a village nearby and learn of a prophecy from the Naku, a tribe they meet: whoever talks to a Smilodon that they call the "Spear-Tooth" will help free their people. D'Leh realizes the prophecy is about him when the same Smilodon that he rescued arrives, but instead refuses to kill D'Leh as it recognized him before leaving. The group also learn that D'Leh's father, the chief of the Yagahl, was a guest of the Naku and learned from them until the slavers took him captive and Tic'Tic finally reveals to D'Leh why his father left.
Another argument for sociality is based on the healed injuries in several Smilodon fossils, which would suggest that the animals needed others to provide it food.[64] This argument has been questioned, as cats can recover quickly from even severe bone damage and an injured Smilodon could survive if it had access to water.[65] The brain of Smilodon was relatively small compared to other cat species. Some researchers have argued that Smilodon's brain would have been too small for it to have been a social animal.[66] An analysis of brain size in living big cats found no correlation between brain size and sociality.[67] Another argument against Smilodon being social is that being an ambush hunter in closed habitat would likely have made group-living unnecessary, as in most modern cats.[65] Yet it has also been proposed that being the largest predator in an environment comparable to the savanna of Africa, Smilodon may have had a social structure similar to modern lions, which possibly live in groups primarily to defend optimal territory from other lions (lions are the only social big cats today).[45]
Despite being more powerfully built than other large cats, Smilodon had a weaker bite. Modern big cats have more pronounced zygomatic arches, while these were smaller in Smilodon, 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 (the bite force quotient measured for the lion is 112).[53][54] There seems to be a general rule that the saber-toothed cats with the largest canines had proportionally weaker bites. 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.[55] In addition, Smilodon's gape could have reached almost 120 degrees,[56] while that of the modern lion reaches 65 degrees.[57] This made the gape wide enough to allow Smilodon to grasp large prey despite the long canines.[36] A 2018 study compared the killing behaviour of Smilodon fatalis and Homotherium serum, and found that the former had a strong skull with little trabecular bone for a stabbing canine-shear bite, whereas the latter had more trabecular bone and used a clamp and hold style more similar to lions. The two would therefore have held distinct ecological niches.[58]
An apex predator, Smilodon primarily hunted large mammals. Isotopes preserved in the bones of S.fatalis in the La Brea Tar Pits reveal that ruminants like bison (Bison antiquus, which was much larger than the modern American bison) and camels (Camelops) were most commonly taken by the cats there.[38] In addition, isotopes preserved in the tooth enamel of S.gracilis specimens from Florida show that this species fed on the peccary Platygonus and the llama-like Hemiauchenia.[39] In rare cases, Smilodon may have also targeted glyptodonts, based on a Glyptotherium skull that bears elliptical puncture marks[40] consistent with the size and diameter of its canine teeth.[41] This was a juvenile glyptodont with an incompletely developed cephalic shield (head armor).[40] Isotopic studies of dire wolf (Canis dirus) and American lion (Panthera leo atrox) bones show an overlap with S.fatalis in prey, which suggests that they were competitors.[38] The availability of prey in the Rancho La Brea area was likely comparable to modern East Africa.[42] As Smilodon migrated to South America, its diet changed; bison were absent, the horses and proboscideans were different, and native ungulates such as toxodonts and litopterns were completely unfamiliar, yet S.populator thrived as well there as its relatives in North America.[13] The differences between the North and South American species may be due to the difference in prey between the two continents.[8] Smilodon probably avoided eating bone and would have left enough food for scavengers.[43] Smilodon itself may have scavenged dire wolf kills.[44] It has been suggested that Smilodon was a pure scavenger that used its canines for display to assert dominance over carcasses, but this theory is not supported today as no modern terrestrial mammals are pure scavengers.[45]
Several Smilodon fossils show signs of ankylosing spondylitis, hyperostosis and trauma;[74] some also had arthritis, which gave them fused vertebrae. One study of 1,000 Smilodon skulls found that 30% of them had eroded parietal bones, which is where the largest jaw muscles attach. They also showed signs of microfractures, and the weakening and thinning of bones possibly caused by mechanical stress from the constant need to make stabbing motions with the canines.[75] Bony growths where the deltoid muscle inserted in the humerus is a common pathology for a La Brea specimen, which was probably due to repeated strain when Smilodon attempted to pull down prey with its forelimbs. Sternum injuries are also common, probably due to collision with prey. Some bones also show evidence of having been bitten by other Smilodon, with one skull showing an unhealed wound from a canine, seemingly fatal, and a scapula from the same site that had been pierced by a canine.[45] The frequency of trauma in S. fatalis specimens was 4.3%, compared to 2.8% in the dire wolf, which implies the ambush predatory behavior of the former led to greater risk of injury than the pursuit predatory behavior of the latter. Smilodon remains exhibit relatively more shoulder and lumbar vertebrae injuries.[76]
Traditionally, saber-toothed cats have been artistically restored with external features similar to those of extant felids, by artists such as Charles R. Knight in collaboration with various paleontologists in the early 20th century.[34] In 1969, paleontologist G.J. Miller instead proposed that Smilodon would have looked very different from a typical cat and similar to a bulldog, with a lower lip line (to allow its mouth to open wide without tearing the facial tissues), a more retracted nose and lower-placed ears.[35] Paleoartist Mauricio Antón and coauthors disputed this in 1998 and maintained that the facial features of Smilodon were overall not very different from those of other cats. Antón noted that modern animals like the hippopotamus are able to achieve a wide gap without tearing tissue by the moderate folding of the orbicularis oris muscle, and such a muscle configuration exists in modern large felids.[36] Antón stated that extant phylogenetic bracketing (where the features of the closest extant relatives of a fossil taxon are used as reference) is the most reliable way of restoring the life-appearance of prehistoric animals, and the cat-like Smilodon restorations by Knight are therefore still accurate.[34]
The question of sociality is still controversial. Strong support for the traditional concept of a solitary Smilodon is found in its brain. Most social predators, including humans, grey wolves, and lions, have brains that are slightly larger than those of their loner relatives. Smilodon had a relatively small brain, suggesting less ability for complex cooperative behaviors, such as hunting in groups.[43] The high numbers of Smilodon in the tar pits is often dismissed as evidence for a social nature because the golden eagle, a species still extant, is solitary and yet is found in the pits in similar numbers. The social grey wolf and coyote lived in the region, but their fossils in the pits are rare.
Radiocarbon analysis of human remains from the cave returned dates of 2390+/-145 B.P. and 1690+/-115 B.P. These remains were collected from an upper zone approximately 16-feet above the saber-tooth bones. The human remains are believed to be from the Woodland Period and originated thousands of years after the "Smilodon" find. According to Guilday (1977), collagen from the "Smilodon" remains returned radiocarbon dates of 9410+/-155 B.P. and 10,035+/-650 B.P. These dates are extremely late for the presence of "Smilodon" in the Southeast, both contemporaneous with the Dalton horizon and overlapping Paleoindian occupations along the Cumberland River by at least 1,000 years. As such, the dates for the "Smilodon" remains from the First American site should be regarded with some skepticism.
In North America, Smilodon hunted large herbivores such as bison and camels, and it remained successful even when encountering new prey species in South America. Smilodon is thought to have killed its prey by holding it still with its forelimbs and biting it, but it is unclear in what manner the bite itself was delivered. Scientists debate 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. Smilodon probably lived in closed habitats such as forests and bush, which would have provided cover for ambushing prey. Smilodon died out at the same time that most North and South American megafauna disappeared, about 10,000 years ago. Its reliance on large animals has been proposed as the cause of its extinction, along with climate change and competition with other species, but the exact cause is unknown.
Whether Smilodon was sexually dimorphic has implications for its reproductive behavior. Based on their conclusions that Smilodon fatalis had no sexual dimorphism, Van Valkenburgh and Sacco suggested in 2002 that, if the cats were social, they would likely have lived in monogamous pairs (along with offspring) with no intense competition among males for females.[26] Likewise, Meachen-Samuels and Binder (2010) concluded that aggression between males was less pronounced in S.fatalis than in the American lion.[27] Christiansen and Harris (2012) found that, as S.fatalis did exhibit some sexual dimorphism, there would have been evolutionary selection for competition between males.[28] The structure of the hyoid bones suggest that Smilodon communicated by roaring, like modern big cats.[68] The ability to roar may have implications for the social life of Smilodon.[69]
Debate continues as to how Smilodon killed its prey. Traditionally, the most popular theory is that the cat delivered a deep stabbing bite or open-jawed stabbing thrust to the throat, generally cutting through the jugular vein and/or the trachea and thus killing the prey very quickly.[49][50] Another hypothesis suggests that Smilodon targeted the belly of its prey. This is disputed, as the curvature of their prey's belly would likely have prevented the cat from getting a good bite or stab.[51] In regard to how Smilodon delivered its bite, the "canine shear-bite" hypothesis has been favored, where flexion of the neck and rotation of the skull assisted in biting the prey, but this may be mechanically impossible. The mandibular flanges may have helped resist bending forces when the mandible was pulled against the hide of a prey.[52] The protruding incisors were arranged in an arch, and were used to hold the prey still and stabilize it while the canine bite was delivered. The contact surface between the canine crown and the gum was enlarged, which helped stabilize the tooth and helped the cat sense when the tooth had penetrated to its maximum extent. Since saber-toothed cats generally had a relatively large infraorbital foramen (opening) in the skull, which housed nerves associated with the whiskers, it has been suggested the improved senses would have helped the cats' precision when biting outside their field of vision, and thereby prevent breakage of the canines. The blade-like carnassial teeth were used to cut skin to access the meat, and the reduced molars suggest that they were less adapted for crushing bones than modern cats.[45] As the food of modern cats enters the mouth through the side while cutting with the carnassials, not the front incisors between the canines, the animals do not need to gape widely, so the canines of Smilodon would likewise not have been a hindrance when feeding.[36]
Smilodon is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals, and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related to the tiger or other modern cats. Smilodon lived in the Americas during the Pleistocene epoch (2.5 mya–10,000 years ago). The genus was named in 1842, based on fossils from Brazil. Three species are recognized today: S.gracilis, S.fatalis, and S.populator. The two latter species were probably descended from S.gracilis, which itself probably evolved from Megantereon. The hundreds of individuals obtained from the La Brea Tar Pits in Los Angeles constitute the largest collection of Smilodon fossils.