Phylogenetic analysis recovered
Smilodon as a
diurnal predator.
S. fatalis had proportionally larger
hyoid bones than modern felid species and thus likely produced deeper vocalizations. While
Smilodon had the same number of hyoid bones as the
roaring cats, their shape was closer to that of
purring species. 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. By finding of correlation between relative
cribriform plate size and repertoire of functional
olfactory receptor genes, it was found that
S. fatalis had a slightly smaller repertoire than modern felids with 600 olfatory receptor genes, compared to 677 of a
domestic cat. This indicates that
S. fatalis used less olfaction for its daily activities than modern felids.
Limb movements Smilodon was likely an
ambush predator that concealed itself in dense vegetation, as its limb proportions were similar to modern forest-dwelling cats, and its short tail would not have helped it balance while running. 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. The
heel bone of
Smilodon was fairly long, which suggests it was a good jumper.
Diet skull with probable S. fatalis'' bite marks,
American Museum of Natural History 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.
S. fatalis may have also occasionally preyed upon
Glyptotherium, based on a skull from a juvenile
G. texanum recovered from Pleistocene deposits in Arizona that bear the distinctive elliptical puncture marks best matching those of
Smilodon, indicating that the predator successfully bit into the skull through the glyptodont's armored cephalic shield. 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. Stable carbon isotope measurements of
S. gracilis remains in Florida varied significantly between different sites and show that the species was flexible in its feeding habits. During the glacials,
S. gracilis has overlapping values with
Edward’s wolf (
Canis edwardii), suggesting greater levels of competition for grazing herbivores. In contrast, during interglacials
S. gracilis preyed upon browsers and niche partitioned with
Canis edwardii, who still preferred grazing prey.
Dental microwear shows a trend of
S. gracilis consuming harder, tougher foods during glacials as compared to interglacials. This finding suggests that
S. gracilis preyed more heavily on larger mixed feeders with tougher hides during glacials, in contrast to interglacials, in which
S. gracilis preferred soft-skinned browsers. Isotopic studies of
dire wolf (
Aenocyon dirus) and
American lion (
Panthera atrox) bones show an overlap with
S. fatalis in prey in
Rancho La Brea, which suggests that they were competitors. The availability of prey in the Rancho La Brea area was likely comparable to modern East Africa.
group in Brazil, in a landscape also including the gomphothere Notiomastodon platensis,
the horse Equus neogeus and the ground sloth Catonyx cuvieri'' 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. Regressions suggests that a
S. populator is capable of taking on prey up to with a pack of
S. populator potentially being capable of taking down fully grown megaherbivores such as
Megatherium and
Notiomastodon. Within the Poço Redondo, Sergipe state of the Brazilian Intertropical Region, the main prey of
S. populator consisted of rhinoceros-like ungulate
Toxodon platensis, the large armadillo relatives
Pachyarmatherium,
Holmesina, species of the
glyptodont genus
Panochthus, the llama
Palaeolama, the ground sloth
Catonyx, and the equine
Equus neogeus, and the crocodilian
Caiman latirostris. This analysis of its diet also indicates that
S. populator hunted both in open and forested habitats within the Brazilian Intertropical Region. However, a more detailed analysis found the main prey of
S. populator within the Brazilian Intertropical Region mainly predated upon
Nothrotherium maquinense.
Coprolites assigned to
S. populator recovered from Argentina preserve
osteoderms from the ground sloth
Mylodon and a
Lama scaphoid bone. In addition to this unambiguous evidence of bone consumption, the coprolites suggest that
Smilodon had a more generalist diet than previously thought. Examinations of dental microwear from La Brea further suggests that
Smilodon consumed both flesh and bone.
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.
Bite mechanics ; the tip points to the right The canines of
Smilodon were fragile by the sides due to their flattened shape 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. Additionally, a comparative finite element analysis between
S. fatalis and
Barbourofelis fricki found the skull of the former to be much less well suited for withstanding the stresses associated with biting relative to that of the latter. 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, killing the prey very quickly. 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. 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. However, evidence from comparisons with
Homotherium suggest that
Smilodon was fully capable of and utilized the canine shear-bite as its primary means of killing prey, based on the fact that it had a thick skull and relatively little trabecular bone, while
Homotherium had both more trabecular bone and a more lion-like clamping bite as its primary means of attacking prey. The discovery, made by Figueirido and Lautenschlager
et al., published in 2018 suggests extremely different ecological adaptations in both machairodonts. The mandibular flanges may have helped resist bending forces when the mandible was pulled against the hide of a prey animal. It has been experimentally proven by means of a machine that recreates the teeth, and simulates the movements of jaws and neck of
Smilodon fatalis (The "Robocat") on bison and elk carcasses, that the stabbing bite to the throat is a much more plausible and practical killing technique than the stabbing bite to the belly. bite while feeding, by Antón 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. 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. 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
Smilodons 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). The bite force of
S. fatalis has been estimated as 1283.74 N at the canine and 4671.41 N at the carnassial, forces comparable to the bite force of the much smaller jaguar. 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. In addition,
Smilodon gape could have reached over 110°, while that of the modern lion reaches 65°. This made the gape wide enough to allow
Smilodon to grasp large prey despite the long canines. The supplementary materials of a 2020 study suggested
S. gracilis and
S. populator had a jaw gape of 89.13° and 82.05° respectively.
Social behavior Paramylodon, one mired, at the
La Brea Tar Pits, by Knight, 1921 Scientists debate whether
Smilodon was
social. One study of African predators found that social predators like lions and spotted hyenas respond more to the
distress calls of prey than solitary species. Since
S. fatalis fossils are common at the La Brea Tar Pits, and were likely attracted by the distress calls of stuck prey, this could mean that this species was social as well. One critical study claims that the study neglects other factors, such as body mass (heavier animals are more likely to get stuck than lighter ones), intelligence (some social animals, like the American lion, may have avoided the tar because they were better able to recognize the hazard), lack of visual and olfactory lures, the type of audio lure, and the length of the distress calls (the actual distress calls of the trapped prey animals would have lasted longer than the calls used in the study). The author of that study ponders what predators would have responded if the recordings were played in India, where the otherwise solitary tigers are known to aggregate around a single carcass. The authors of the original study responded that though effects of the calls in the tar pits and the playback experiments would not be identical, this would not be enough to overturn their conclusions. In addition, they stated that weight and intelligence would not likely affect the results as lighter carnivores are far more numerous than heavy herbivores and the social (and seemingly intelligent) dire wolf is also found in the pits. However, they do not rule out the possibility that
Smilodon may have been solitary in part of its distribution. Another argument for sociality is based on the healed injuries in several
Smilodon fossils, which would suggest that the animals needed others to provide them food. 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. However, pathological analysis on dental injuries largely suggests that injured individuals ate softer flesh than non-injured individuals, the authors argued this, along with consideration the individuals survived for a good amount of time from the injuries, may be evidence of
Smilodon forming social groups. The brain of
Smilodon was relatively small compared to other cat species. Some researchers have argued that
Smilodon brain would have been too small for it to have been a social animal. An analysis of brain size in living big cats found no correlation between brain size and sociality. 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. It has been suggested that the exaggerated canines of saber-toothed cats evolved for
sexual display and competition, but a statistical study of the correlation between canine and body size in
S. populator found no difference in scaling between body and canine size concluded it was more likely they evolved solely for a predatory function. '', by Knight, 1931 A set of three associated skeletons of
S. fatalis found in Ecuador and described in 2021 by Reynolds, Seymour, and Evans suggests that there was prolonged parental care in
Smilodon. The two subadult individuals uncovered share a unique inherited trait in their dentaries, suggesting they were siblings; a rare instance of familial relationships being found in the fossil record. The subadult specimens are also hypothesized to have been male and female, respectively, while the adult skeletal remains found at the site are believed to have belonged to their mother. The subadults were estimated to have been around two years of age at the time of their deaths, but were still growing. If
S. populator practiced a gregarious lifestyle, the optimal group size would have been around four individuals.
Development Smilodon started developing its adult saber-teeth when the animal reached between 12 and 19 months 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 approximately 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 reached 23 to 30 months of age, the infant teeth were shed while the adult canines grew at an average growth rate of per month during a 12-month period. They reached their full size at around 3 years of age, later than modern species of big cats. 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.
Finite element analysis and three-dimensional geometric morphometrics of the mandibles of juvenile
S. fatalis show they were poorly suited for performing anchor bites, further suggesting an extended period of parental care for the species. A 2024 study found evidence that adolescent
Smilodon kept their milk sabers for extended periods (estimated at 30 months) to help reinforce their adult canines as they grew in. As a result, the milk sabers acted as a structural support, allowing them to begin hunting with minimized risk to their mature set of sabers. As a result, the retention of the cat's milk sabers lessened the bending strain on the cat's emerging adult teeth as it bit down, as it was discovered the erupting sabers were much more vulnerable to breakage as they grew in than when matured. This would have also resulted in
Smilodon being "double-fanged" during this growth stage, as corroborated by the discovery of individuals at this ontogenic stage at Rancho La Brea. A 2017 study indicates that juveniles were born with a robust build similar to the adults. Comparison of the bones of juvenile
S. fatalis specimens from La Brea with those of the contemporaneous American lion revealed that the two cats shared a similar growth curve. Felid forelimb development during
ontogeny (changes during growth) has remained tightly constrained. The curve is similar to that for modern cats such as tigers and cougars, but shifts more towards the robust direction of the axes than is seen in modern felids. Examinations by Reynolds, Seymour, and Evans (2021) suggest that
Smilodon had a unique and fast growth rate similar to a tiger, but that there was a prolonged period of growth in the genus similar to what is seen in lions, and that the cubs were reliant on their parents until this growth period ended.
Paleopathology Several
Smilodon fossils show signs of
ankylosing spondylitis,
hyperostosis and trauma. One study of 1,000
Smilodon skulls found that 36% 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. 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. A 2023 study documented a high degree of
subchondral defects in limb-joint surfaces of
S. fatalis and dire wolf specimens from the La Brea Tar Pits that resembled
osteochondrosis dissecans. As modern dogs with this disease are
inbred, the researchers suggested this would have been the case for the prehistoric species as well as they approached extinction, but cautioned that more research was needed to determine if this was also the case in specimens from other parts of the Americas. in
S. fatalis limb-joints (arrows) Some
S. fatalis specimens from the La Brea Tar Pits exhibit substantially decreased mandibular
cortical bone thickness, which has been interpreted as a consequence of nutritional stress in those individuals. The frequency of this low cortical bone thickness appears to have been variable over geologic time, being low during the time of the final demise of the species.
Osteomyelitis in the left
fourth metacarpal bone has been reported in a
S. populator specimen dating back to
Marine Isotope Stage 5. This pathology resulted in the machairodont individual becoming incapable of flexing its toe and would have severely diminished its ability to hunt prey.
Natural traps over a
Columbian mammoth carcass in the La Brea Tar Pits, by
Robert Bruce Horsfall, 1913 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 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. 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. == Distribution and habitat ==