Instruct: Given a question, retrieve relevant passages that can help answer the question.
Query: Where were fossils of the Smilodon first discovered?
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.
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.
Cerro de los Batallones ("Hill of the Battalions") is a hill at Torrejón de Velasco, Madrid, Spain where a number of fossil sites from the Upper Miocene (MN10) have been found. Nine sites have been discovered with predominately vertebrate fossils, invertebrates and plants being less represented. The first deposits were discovered accidentally in July 1991.
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]
Ancient people living near Fossil, Oregon collected fossils as far back as 11,000 years ago and kept them at a dwelling that has since been uncovered by archeologists. Some of the fossils kept there were pierced to be made into jewelry. Five slabs of rock bearing leaf impressions were found neatly stacked in the corner of the site. These and other fossils discovered by Native Americans may have contributed to the development of local myths and lore. Historian Adrienne Mayor cites as an example the Klamath Tribes of the Modoc, who attributed local fossils to water monsters killed by the mythological figure Coyote.
Oregon's first paleontologist was Thomas Condon. Condon began collecting in 1861, when a company of soldiers that arrived in Fort Dalles, where Condon served as the Congregational church pastor. The soldiers brought fossil bones and teeth, including a well-preserved rhinoceros jaw, from the John Day fossil beds. When soldiers were dispatched the following year to Harney Valley, near the fossil beds, Condon went along with them and prospected for fossils. He went fossil collecting again in 1863 and discovered rich fossil deposits north of Picture Gorge in the John Day River valley.
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]
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]
Smilodon was around the size of modern big cats, but was more robustly built. It had a reduced lumbar region, high scapula, short tail, and broad limbs with relatively short feet.[23][24] Smilodon is most famous for its relatively long canine teeth, which are the longest found in the saber-toothed cats, at about 28cm (11in) long in the largest species, S. populator.[23] The canines were slender and had fine serrations on the front and back side.[25] The skull was robustly proportioned and the muzzle was short and broad. The cheek bones (zygomata) were deep and widely arched, the sagittal crest was prominent, and the frontal region was slightly convex. The mandible had a flange on each side of the front. The upper incisors were large, sharp, and slanted forwards. There was a diastema (gap) between the incisors and molars of the mandible. The lower incisors were broad, recurved, and placed in a straight line across. The p3 premolar tooth of the mandible was present in most early specimens, but lost in later specimens; it was only present in 6% of the La Brea sample.[3] There is some dispute over whether Smilodon was sexually dimorphic. Some studies of S. fatalis fossils have found little difference between the sexes.[26][27] 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.[28]
Along with most of the Pleistocene megafauna, Smilodon became extinct 10,000 years ago in the Quaternary extinction event. Its extinction has been linked to the decline and extinction of large herbivores, which were replaced by smaller and more agile ones like deer. Hence, Smilodon could have been too specialized at hunting large prey and may have been unable to adapt.[49] A 2012 study of Smilodon tooth wear found no evidence that they were limited by food resources.[83] Other explanations include climate change and competition with humans[83] (who entered the Americas around the time Smilodon disappeared), or a combination of several factors, all of which apply to the general Pleistocene extinction event, rather than specifically to the extinction of the saber-toothed cats.[84]
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]
The lineage of "Homotherium" is estimated (based on mitochondrial DNA sequences) to have diverged from that of "Smilodon" about 18 million years ago. "Homotherium" probably derived from "Machairodus" and appeared for the first time at the Miocene–Pliocene border, about 4 to 5 million years ago. During the Pleistocene it occurred in vast parts of Eurasia, North America and until the middle Pleistocene (about 1.5 million years ago) even in Africa. A fossil of "H. crenatidens" was inadvertently dredged from the bed of the North Sea, which was a flat, low-lying extent of marshy tundra laced with rivers during the last glacial period. There has also been a discovery of 1.8-million-year-old fossils in Venezuela, indicating that scimitar-toothed cats were able to invade South America along with "Smilodon" during the Great American Interchange. These remains form the holotype of "Homotherium venezuelensis". How long they lasted in South America is not yet evident. "Homotherium" survived in Eurasia until about 28,000 years ago.
The first fossils of "Pseudobornia" were collected by Johan Gunnar Andersson on Bear Island in the 1890s. Hans-Joachim Schweitzer, a paleobotanist, was the first to interpret the fossils as belonging to a large tree, based on additional fossils discovered in Alaska in the 1960s.The probable relationships within Equisetopsida are shown in the cladogram below. The position where "Ibyka" would be has been added.
In 1912 he was appointed chairman of the Department of Paleontology at the University of California. That same year he began his famous studies of vertebrates at the La Brea Tar Pits. He and his students categorized many of the vertebrate fossils found at the site, and many more were placed in storage. The smilodon was later established as the California state fossil.
In October 2014, the fossil remains of an early hominin were discovered at the site. A mandible and six teeth were discovered. The hominin fossils belonged to at least three distinct individuals. The hominin fossils were dated to around 700,000 BP, making the Mata Menge fossils the oldest hominin fossils yet discovered on the island of Flores. The fossils at Mata Menge are likely to belong to hominins that resulted from the effects of insular dwarfism working on "Homo erectus".
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]
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]
Ichthyosaur fossils of the species "Shonisaurus popularis" were first discovered in the area in 1928. Excavations were conducted through the 1960s, and the remains of approximately 40 ichthyosaurs were found. Until 2004, these remains included the largest ichthyosaurs ever discovered. Several specimens were left where they were found, and can be viewed by the public. These specimens are protected from the elements by a large barn. The fossils are about a 10-minute drive from the Berlin ghost town. The ichthyosaur fossils were designated a National Natural Landmark in 1973.
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.
Afontova Gora II is the site where the human fossil remains were found. The site was first excavated in 1912-1914 by V.I. Gromov. In 1924, G.P. Sosnovsky, N.K. Auerbach, and V.I. Gromov discovered the first human fossils at the site. The remains of mammoth, Arctic fox, Arctic hare, reindeer, bison, and horse were discovered at the site.
Local Native Americans devised myths to explain local fossils, many containing themes paralleling modern scientific discoveries. Local fossils came to the attention of formally trained scientists by the mid-19th century. Major finds include the Pleistocene mammal fossils of the La Brea tar pits. The Pleistocene saber-toothed cat "Smilodon fatalis" is the California state fossil.
The Talara Tar Seeps in Peru represent a similar scenario, and have also produced fossils of Smilodon. Unlike in La Brea, many of the bones were broken or show signs of weathering. This may have been because the layers were shallower, so the thrashing of trapped animals damaged the bones of previously trapped animals. Many of the carnivores at Talara were juveniles, possibly indicating that inexperienced and less fit animals had a greater chance of being trapped. Though Lund thought accumulations of Smilodon and herbivore fossils in the Lagoa Santa Caves were due to the cats using the caves as dens, these are probably the result of animals dying on the surface, and water currents subsequently dragging their bones to the floor of the cave, but some individuals may also have died after becoming lost in the caves.[60]
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]
In his 1880 article about extinct cats, Cope also named a third species of Smilodon, S.gracilis. The species was based on a partial canine, which had been obtained in a cave near the Schuylkill River in Pennsylvania. Cope found the canine to be distinct from that of the other Smilodon species due to its smaller size and more compressed base.[7] Its specific name refers to the species' lighter build.[9] This species is known from fewer and less complete remains than the other members of the genus.[10] S.gracilis has at times been considered part of genera such as Megantereon and Ischyrosmilus.[11] S.populator, S.fatalis and S.gracilis are currently considered the only valid species of Smilodon, and features used to define most of their junior synonyms have been dismissed as variation between individuals of the same species (intraspecific variation).[4][3] One of the most famous of prehistoric mammals, Smilodon has often been featured in popular media and is the state fossil of California.[1]
The first documented fossils to be recovered from the Bridger Formation were discovered on 11 August 1849 by Captain Howard Stansbury, who documented the discovery of fossilized shells and wood in his expedition report while scouting out the region for the United States Army Corps of Topographical Engineers. In the early-1860s, trapper Jack Robinson claimed to have discovered a number of sites along the base of the Uinta Mountains where grizzly bears had been turned to stone. When these claims were called into question by judge William A. Carter, Robinson brought Carter a bag filled with the fossils. One of the specimens recovered by Robinson was a well-preserved skull which resembled that of a grizzly bear. Judger Carter invited Louis Agassiz to observe the local strata, but Agassiz declined as the journey would have involved riding horseback to the site, a mode of transportation Agassiz abhorred. Carter's son-in-law, Dr. J. Van A. Carter, would go on to send a number of fossils to palaeontologist Joseph Leidy at the University of Pennsylvania in 1869. These fossils included the first Bridgerian fossil taxa, "Omomys carteri"; and the skull discovered by Robinson, which was described as "Palaeosyops paludosus". Another researcher responsible for sending off specimens was Dr. Joseph K. Corson, a close friend of Leidy's who hosted him and his family on two three to Fort Bridger in 1872, 1873, and 1879.
Elgin Reptiles is the name given to the Permian and Triassic fossils found in the sandstone deposits in and around the town of Elgin, in Moray, Scotland. They are of great historical and scientific importance, and many of the specimens are housed in the Elgin Museum, and some in the Hunterian in Glasgow, and the National Museum of Scotland in Edinburgh. The Elgin Reptiles include the dinosauriform "Saltopus elginensis", the dicynodont "Gordonia", and the pareiasaur "Elginia". There are also many footprints and tail-drags associated with the same Permian and Triassic sandstone deposits.
The sandstone in the Elgin area was originally quarried for building materials. The quarries were where the first reptile fossils were found, and they have continued to yield fossils to this day.
The first Elgin Reptile was discovered in 1844, but because it was only a few scales scientists of the time believed it was an Old Red Sandstone fish fossil, which were relatively well-known from sites across Northern Scotland. In 1851 a second indisputably reptilian fossil was found. Fossils of "Gordonia" were first found by Scottish naturalist Ramsay Heatley Traquair in 1885 and E.T. Newton described several key fossil specimens.