Instruct: Given a question, retrieve passages that can help answer the question.
Query: How large was the Smilodon?
Overall, "Smilodon" was more robustly built than any extant cat, with particularly well-developed forelimbs and exceptionally long upper canine teeth. Its jaw had a bigger gape than that of modern cats, and its upper canines were slender and fragile, being adapted for precision killing. "S. gracilis" was the smallest species at in weight. "S. fatalis" had a weight of and height of . Both of these species are mainly known from North America, but remains from South America have also been attributed to them. "S. populator" from South America was the largest species, at in weight and in height, and was among the largest known felids. The coat pattern of "Smilodon" is unknown, but it has been artistically restored with plain or spotted patterns.
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.
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.
The jaws of machairodonts, especially more derived species with longer canines, such as "Smilodon" and "Megantereon", are unusually weak. Digital reconstructions of the skulls of lions and of "Smilodon" show that the latter would have fared poorly with the stresses of holding onto struggling prey. The main issue was the stresses suffered by the mandible: a strong force threatened to break the jaw as pressure was placed on its weakest points.
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.
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. Likewise, Meachen-Samuels and Binder (2010) concluded that aggression between males was less pronounced in "S. fatalis" than in the American lion. Christiansen and Harris (2012) found that, as "S. fatalis" did exhibit some sexual dimorphism, there would have been evolutionary selection for competition between males. The structure of the hyoid bones suggest that "Smilodon" communicated by roaring, like modern big cats. The ability to roar may have implications for the social life of "Smilodon".
"Dimetrodon" was a quadrupedal, sail-backed synapsid. Most "Dimetrodon" species ranged in length from and are estimated to have weighed between . The largest known species of "Dimetrodon" is "D. angelensis" at and the smallest is "D. teutonis" at . The larger species of "Dimetrodon" were among the largest predators of the Early Permian, although the closely related "Tappenosaurus", known from skeletal fragments in slightly younger rocks, may have been even larger at an estimated in total body length. Although some "Dimetrodon" species could grow very large, many juvenile specimens are known.
"Brontosaurus" was a large, long-necked quadrupedal animal with a long, whip-like tail, and forelimbs that were slightly shorter than its hindlimbs. The largest species, "B. excelsus", weighed up to and measured up to long from head to tail. For comparison, the current largest land animal, the average male African bush elephant is 3.20 m (10.5 ft) tall at the shoulder and has a body mass of 6,000 kg (13,228 lb) or 6.6 short tons.
Dimetrodon ( or , meaning "two measures of teeth") is an extinct genus of synapsids that lived during the Cisuralian (Early Permian), around 295–272 million years ago (Ma). It is a member of the family Sphenacodontidae. The most prominent feature of "Dimetrodon" is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. It walked on four legs and had a tall, curved skull with large teeth of different sizes set along the jaws. Most fossils have been found in the southwestern United States, the majority coming from a geological deposit called the Red Beds of Texas and Oklahoma. More recently, fossils have been found in Germany. Over a dozen species have been named since the genus was first described in 1878.
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.
Besides its small size, "D. milleri" differs from other species of "Dimetrodon" in that its neural spines are circular rather than figure-eight shaped in cross-section. Its vertebrae are also shorter in height relative to the rest of the skeleton than those of other "Dimetrodon" species. The skull is tall and the snout is short relative to the temporal region. A short vertebrae and tall skull are also seen in the species "D. booneorum", "D. limbatus" and "D. grandis", suggesting that "D. milleri" may be the first of an evolutionary progression between these species.
"Sinosauropteryx" was a small bipedal theropod, noted for its short arms, large first finger (thumbs), and long tail. The taxon includes some of the smallest known adult non-avian theropod specimens, with the holotype specimen measuring only in length, including the tail. However, this individual was relatively young. The longest known specimen reaches up to in length, with an estimated weight of .
The largest land mammal extant today is the African bush elephant. The largest extinct land mammal known was long considered to be "Paraceratherium orgosensis", a rhinoceros relative thought to have stood up to tall, measured over long and may have weighed about 17 tonnes. In 2015, a study suggested that one example of the proboscidean "Palaeoloxodon namadicus" may have been the largest land mammal ever, based on extensive research of fragmentary leg bone fossils from one individual, with a maximum estimated size of 22 tonnes.
A number of partial fossil remains of "Secodontosaurus" have been identified from its characteristic long skull and jaws. The postcranial skeletal material from different individuals includes parts of the backbone with clear evidence of a tall sail very similar to that of "Dimetrodon". The limbs and tail are incomplete but probably resembled those of "Dimetrodon" as well. Like "Dimetrodon", "Secodontosaurus" would have had a short neck, robust body, short limbs, and a long tail. In light of such similarities, some skeletal remains with missing or fragmentary skulls that were previously identified as "Dimetrodon" may in fact belong to "Secodontosaurus". A key noncranial difference can be found in the axis neck vertebra, which has a tall and broad neural spine in "Dimetrodon" but has a lower neural spine in "Secodontosaurus".
Though similar to "Palaeopropithecus", "Archaeoindris" was significantly larger and more robust. "Archaeoindris" was one of the largest primates to ever evolve, and was the largest-known strepsirrhine primate, weighing an estimated . It was roughly the size of an adult male gorilla, which was first noted by Lamberton.
The Permian era "Cotylorhynchus", from what is now the southern United States, probably was the largest of all synapsids (most of which became extinct 250 million years ago), at and 2 tonnes. The largest carnivorous synapsid was "Anteosaurus" from what is now South Africa during Middle Permian era. "Anteosaurus" was long, and weighed about .The largest living reptile, a representative of the order Crocodilia, is the saltwater crocodile ("Crocodylus porosus") of Southern Asia and Australia, with adult males being typically long. The largest confirmed saltwater crocodile on record was long, and weighed about . Unconfirmed reports of much larger crocodiles exist, but examinations of incomplete remains have never suggested a length greater than . Also, a living specimen estimated at and has been accepted by the Guinness Book of World Records. However, due to the difficulty of trapping and measuring a very large living crocodile, the accuracy of these dimensions has yet to be verified. A specimen named Lolong caught alive in the Philippines in 2011 (died February 2013) was found to have measured in length.
The team discovered the remains of the largest dinosaur to walk in the southern parts of Africa , namely a 190-million-year-old fossilised egg of a Massospondylus dinosaur. This dinosaur lived in the Late Triassic and Early Jurassic, a period from about 230-million years ago to about 185-million years ago. The Massospondylus wandered about in great herds, migrating back and forth between what would millions of years later become Southern Africa and Russia, when the southern super-continent, Gondwana, was still intact. The rocks that were laid down during this period are called the Stormberg Group of rocks, and it is in rocks of the Stormberg Group that the fossils of Massospondylus and other dinosaurs were found. Massospondylus dinosaurs hatched from eggs not much larger than a hen’s egg, but grew into big creatures 5 to 6 metres long. They had large bodies, long necks and small heads, and long tails.
Josephoartigasia monesi, an extinct species of South American caviomorph rodent, is the largest rodent known, and lived from about 4 to 2 million years ago during the Pliocene to early Pleistocene. The species is one of two in the genus "Josephoartigasia", the other being "J. magna". "J. monesi" is sometimes called the giant pacarana, after its closest living relative, the pacarana ("Dinomys branickii") in the family Dinomyidae. The species may have weighed a ton, considerably larger than any living rodent.
There were larger dinosaurs, but knowledge of them is based entirely on a small number of fragmentary fossils. Most of the largest herbivorous specimens on record were discovered in the 1970s or later, and include the massive titanosaur "Argentinosaurus huinculensis", which is the largest dinosaur known from uncontroversial evidence, estimated to have been and long. Some of the longest sauropods were those with exceptionally long, whip-like tails, such as the "Diplodocus hallorum" (formerly "Seismosaurus") and the 33- to 35-metre-long (108–115 ft) "Supersaurus". The tallest was the "Brachiosaurus".
Alamosaurus (; meaning "Ojo Alamo lizard") is a genus of titanosaurian sauropod dinosaurs, containing a single known species, Alamosaurus sanjuanensis, from the late Cretaceous Period of what is now southern North America. Isolated vertebrae and limb bones indicate that it reached sizes comparable to "Argentinosaurus" and "Puertasaurus", which would make it the largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age of the late Cretaceous period. Specimens of a juvenile "Alamosaurus sanjuanensis" have been recovered from only a few meters below the Cretaceous-Paleogene boundary in Texas, making it among the last surviving non-avian dinosaur species.
Adult "Pteranodon" specimens may be divided into two distinct size classes, small and large, with the large size class being about one and a half times larger than the small class, and the small class being twice as common as the large class. Both size classes lived alongside each other, and while researchers had previously suggested that they represent different species, Christopher Bennett showed that the differences between them are consistent with the concept that they represent females and males, and that "Pteranodon" species were sexually dimorphic. Skulls from the larger size class preserve large, upward and backward pointing crests, while the crests of the smaller size class are small and triangular. Some larger skulls also show evidence of a second crest that extended long and low, toward the tip of the beak, which is not seen in smaller specimens.
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. 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". In rare cases, "Smilodon" may have also targeted glyptodonts, based on a "Glyptotherium" skull that bears elliptical puncture marks consistent with the size and diameter of its canine teeth. This was a juvenile glyptodont with an incompletely developed cephalic shield (head armor). 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. The availability of prey in the Rancho La Brea area was likely comparable to modern East Africa. 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. The differences between the North and South American species may be due to the difference in prey between the two continents. "Smilodon" probably avoided eating bone and would have left enough food for scavengers. "Smilodon" itself may have scavenged dire wolf kills. 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.
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. A 2012 study of "Smilodon" tooth wear found no evidence that they were limited by food resources. Other explanations include climate change and competition with humans (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.
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.
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. 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.