Where were fossils of the Smilodon first discovered?
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Fossils of "Smilodon" were discovered in North America from the second half of the 19th century onwards. 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". The species name means "fate" or "destiny", but it is thought Leidy intended it to mean "fatal". 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". 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. "S. fatalis" has junior synonyms such as "S. mercerii", "S. floridanus", and "S. californicus". 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". Swedish paleontologists Björn Kurtén and Lars Werdelin supported the distinctness of the two species in 1990.
Smilodon
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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.
Smilodon
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During the 1830s, Danish naturalist Peter Wilhelm Lund and his assistants collected fossils in the calcareous caves near the small town of Lagoa Santa, Minas Gerais, Brazil. Among the thousands of fossils found, he recognized a few isolated cheek teeth as belonging to a hyena, which he named "Hyaena neogaea" in 1839. After more material was found (including canine teeth and foot bones), Lund concluded the fossils instead belonged to a distinct genus of felid, though transitional to the hyenas. He stated it would have matched the largest modern predators in size, and was more robust than any modern cat. Lund originally wanted to name the new genus "Hyaenodon", but realizing this had recently become preoccupied by another prehistoric predator, he instead named it "Smilodon populator" in 1842. He explained the Ancient Greek meaning of "Smilodon" as ("smilē"), a scalpel or two-edged knife, and "οδόντος" ("odontús"), tooth. This has also been translated as "tooth shaped like double-edged knife". He explained the species name "populator" as "the destroyer", which has also been translated as "he who brings devastation". By 1846, Lund had acquired nearly every part of the skeleton (from different individuals), and more specimens were found in neighboring countries by other collectors in the following years. Though some later authors used Lund's original species name "neogaea" instead of "populator", it is now considered an invalid "nomen nudum" ("naked name"), as it was not accompanied with a proper description and no type specimens were designated. Some South American specimens have been referred to other genera, subgenera, species, and subspecies, such as "Smilodontidion riggii", "Smilodon" ("Prosmilodon") "ensenadensis", and "S. bonaeriensis", but these are now thought to be junior synonyms of "S. populator".
Smilodon
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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.
Smilodon
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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.
Homotherium
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"Smilodon" lived during the Pleistocene epoch (2.5 mya–10,000 years ago), and was perhaps the most recent of the saber-toothed cats. "Smilodon" probably lived in a closed habitat such as forest or bush. Fossils of the genus have been found throughout the Americas. 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. 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.
Smilodon
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Rhizosmilodon is an extinct genus of saber-tooth cat of the subfamily Machairodontinae that lived during the Early Pliocene and was discovered in the U.S. state of Florida. Comparable in size to a medium-sized modern jaguar at about 165 lb. in weight, fossils of "Rhizosmilodon" are known only from Florida. The best specimens for this species are its lower jaw and teeth, which carry intermediate characteristics between advanced forms such as "Smilodon" and primitive forms such as "Paramachairodus". It was likely an ambush predator, preying on animals such as deer, tapirs and horses.
Rhizosmilodon
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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. Its specific name refers to the species' lighter build. This species is known from fewer and less complete remains than the other members of the genus. "S. gracilis" has at times been considered part of genera such as "Megantereon" and "Ischyrosmilus". "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). One of the most famous of prehistoric mammals, "Smilodon" has often been featured in popular media and is the state fossil of California.
Smilodon
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Several "Smilodon" fossils show signs of ankylosing spondylitis, hyperostosis and trauma; 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. 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. 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.
Smilodon
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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.
UBS Tower (Nashville)