Editing Smilodon (section)

=== Social life ===
[[File:La Brea Tar Pits.jpg|thumb|left|''S. fatalis'' pair approaching a group of the [[ground sloth]] ''[[Paramylodon]]'', one mired, at the La Brea Tar Pits, by Knight, 1921]]

Scientists debate whether ''Smilodon'' was [[social animal|social]]. One study of African predators found that social predators like [[lion]]s and [[spotted hyena]]s respond more to the [[distress call]]s of prey than solitary species. Since ''S.&nbsp;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.<ref>{{cite journal |last1=Carbone |first1=C. |last2=Maddox |first2=T. |last3=Funston |first3=P. J. |last4=Mills |first4=M. G. L. |last5=Grether |first5=G. F. |last6=Van Valkenburgh |first6=B. |year=2009 |title=Parallels between playbacks and Pleistocene tar seeps suggest sociality in an extinct sabretooth cat, ''Smilodon'' |journal=Biology Letters |doi=10.1098/rsbl.2008.0526 |pmid=18957359 |pmc=2657756 |volume=5 |issue=1 |pages=81–85}}</ref> 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.<ref>{{cite journal |last=Kiffner |first=C. |year=2009 |title=Coincidence or evidence: was the sabretooth cat ''Smilodon'' social? |journal=Biology Letters |doi=10.1098/rsbl.2009.0008 |pmid=19443504 |pmc=2781900 |volume=5 |issue=4 |pages=561–562}}</ref> 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.<ref>{{cite journal |last1=Van Valkenburgh |first1=B. |last2=Maddox |first2=T. |last3=Funston |first3=P. J. |last4=Mills |first4=M. G. L. |last5=Grether |first5=G. F. |last6=Carbone |first6=C. |year=2009 |title=Sociality in Rancho La Brea ''Smilodon'': arguments favour 'evidence' over 'coincidence' |journal=Biology Letters |doi=10.1098/rsbl.2009.0261 |volume=5 |issue=4 |pages=563–564|pmc=2781931 }}</ref>

[[File:Lions hunting a buffalo.jpg|thumb|right|[[Lion]] pride attacking an [[African buffalo]] in [[Tanzania]]; ''Smilodon'' may also have hunted in groups]]
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.<ref>{{cite journal |last=Heald |first=F. |year=1989 |title="Injuries and diseases in ''Smilodon californicus'' Bovard, 1904, (Mammalia, Felidae) from Rancho La Brea, California |journal=Journal of Vertebrate Paleontology |volume=9 |issue=3 |page=24A}}</ref><ref name="dysplasia">{{cite bioRxiv |last1=Balisi |first1=M. A. |last2=Sharma |first2=A. K. |last3=Howard |first3=C. M. |last4=Shaw |first4=C. A. |last5=Klapper |first5=R. |last6=Lindsey |first6=Emily L. |title=Computed tomography reveals hip dysplasia in Smilodon: Implications for social behavior in an extinct Pleistocene predator |date=2020 |biorxiv=10.1101/2020.01.07.897348}}</ref> 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.<ref name="McCall">{{cite journal |last1=McCall |first1=S. |last2=Naples |first2=V. |last3=Martin |first3=L. |year=2003 |title=Assessing behavior in extinct animals: was ''Smilodon'' social? |journal=Brain, Behavior and Evolution |pmid=12697957 |doi=10.1159/000069752 |volume=61 |issue=3 |pages=159–164|s2cid=2756104 |url=https://zenodo.org/record/1235325 }}</ref> 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. <ref name=":1" /> In addition, a ''Smilodon'' suffering hip dysplasia at a young age that survived to adulthood suggests that it could not have survived to adulthood without aid from a social group, as this individual was unable to hunt or defend its territory due to the severity of its congenital issue.<ref>{{Cite journal|url=https://www.biorxiv.org/content/10.1101/2020.01.07.897348v2.full|doi = 10.1101/2020.01.07.897348|title = Computed tomography reveals hip dysplasia in the extinct Pleistocene saber-tooth cat Smilodon|year = 2021|last1 = Balisi|first1 = Mairin A.|last2 = Sharma|first2 = Abhinav K.|last3 = Howard|first3 = Carrie M.|last4 = Shaw|first4 = Christopher A.|last5 = Klapper|first5 = Robert|last6 = Lindsey|first6 = Emily L.|journal = bioRxiv|volume = 11|issue = 1|page = 21271|pmid = 34711910|pmc = 8553773|s2cid = 235663241}}</ref> 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.<ref name="Radinsky">{{cite journal |last=Radinsky |first=L. B. |year=1975 |title=Evolution of the felid brain |journal=Brain, Behavior and Evolution |doi=10.1159/000123636 |pmid=1181005 |volume=11 |issue=3–4 |pages=214–254}}</ref> An analysis of brain size in living big cats found no correlation between brain size and sociality.<ref>{{cite journal |last1=Yamaguchi |first1=N. |last2=Kitchener |first2=A. C. |last3=Gilissen |first3=E. |last4=MacDonald |first4=D. W. |year=2009 |title=Brain size of the lion (''Panthera leo'') and the tiger (''P. tigris''): implications for intrageneric phylogeny, intraspecific differences and the effects of captivity |journal=Biological Journal of the Linnean Society |doi=10.1111/j.1095-8312.2009.01249.x |volume=98 |issue=1 |pages=85–93|doi-access= }}</ref> 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.<ref name="McCall" /> 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).{{Sfn|Antón|2013|pp=176–216}}

[[File:La Brea Tar Pits Museum Injuries Exhibit.jpg|thumb|left|Tip of an ''S. fatalis'' saber imbedded in the rib of another ''S. fatalis'']] 
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 pairing in animals|monogamous pairs]] (along with offspring) with no intense competition among males for females.<ref name="Van Valenburgh" /> Likewise, Meachen-Samuels and Binder concluded in 2010 that aggression between males was less pronounced in ''S.&nbsp;fatalis'' than in the American lion.<ref name="Meachen-Samuels" /> Christiansen and Harris found in 2012 that, as ''S.&nbsp;fatalis'' did exhibit some sexual dimorphism, suggesting there would have been evolutionary selection for competition between males. They also argued because of the larger body size within male specimens, they would’ve preferred larger prey compared to females, possibly suggesting sexually determined resource partitioning. Due to the lack of skewed bias towards one sex, the authors concluded if ''S. fatalis'' was social, it probably lived in unisexual groups and practiced polygamy instead of monogamy.<ref name="Christiansen" /> Some bones show evidence of having been bitten by other ''Smilodon'', possibly the result of territorial battles, competition for breeding rights or over prey.{{Sfn|Antón|2013|pp=176–216}} Two ''S. populator'' skulls from Argentina show seemingly fatal, unhealed wounds which appear to have been caused by the canines of another ''Smilodon'' (though it cannot be ruled out they were caused by kicking prey). If caused by intraspecific fighting, it may also indicate that they had social behavior which could lead to death, as seen in some modern felines (as well as indicating that the canines could penetrate bone).<ref name="Chimento2019">{{cite journal|last1= Chimento|first1=N. R.|last2= Agnolin|first2=F. L.|last3= Soibelzon|first3= L.|last4= Ochoa|first4=J. G.|last5= Buide|first5= V.|title= Evidence of intraspecific agonistic interactions in ''Smilodon populator'' (Carnivora, Felidae)|journal= Comptes Rendus Palevol|volume=18|issue=4|pages=449–454|year= 2019|doi= 10.1016/j.crpv.2019.02.006|bibcode=2019CRPal..18..449C |doi-access= free}}</ref> 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.<ref>{{cite journal |last1=O’Brien |first1=D. M |title=Static scaling and the evolution of extreme canine size in a saber-toothed cat (''Smilodon fatalis'') |journal=Integrative and Comparative Biology |volume=59 |issue=5 |pages=1303–1311 |date=2019 |doi=10.1093/icb/icz054|pmid=31120517 |doi-access=free }}</ref>

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.<ref name="Reynolds, Seymour, and Evans 2021" />   

Different results in isotopic analysis studies may suggest ''S. populator'' social behavior  varied depending on the locality. In the Pampean region of Argentina, ''Smilodon'' may have lived a gregarious lifestyle due tight clustering of isotopic values, which may suggest collective behavior.<ref name=":0" /> While in the Brazilian intertropical region, this species lived a more solitary lifestyle due to the lower percentage of prey in the optimum body mass interval, as gregarious predators have at least 65% of their prey within optimum body mass interval.<ref>{{Cite journal |last1=Dantas |first1=Mário André Trindade |last2=Bernardes |first2=Camila |last3=Asevedo |first3=Lidiane |last4=Rabito Pansani |first4=Thaís |last5=De Melo França |first5=Lucas |last6=Santos De Aragão |first6=Wilcilene |last7=Da Silva Santos |first7=Franciely |last8=Cravo |first8=Elisa |last9=Ximenes |first9=Celso |date=4 March 2022 |title=Isotopic palaeoecology ( δ 13 C) of three faunivores from Late Pleistocene of the Brazilian intertropical region |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2021.1933468 |journal=[[Historical Biology]] |language=en |volume=34 |issue=3 |pages=507–514 |bibcode=2022HBio...34..507D |doi=10.1080/08912963.2021.1933468 |issn=0891-2963 |access-date=2 May 2024 |via=Taylor and Francis Online}}</ref> 

''S. fatalis'' had proportionally larger [[hyoid bone]]s 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 "[[purr]]ing" species.<ref name="Deuthsch">{{cite journal|last1=Deutsch|first1=A. R.|last2=Langerhans|first2=R. B.|last3=Flores|first3=D|last4=Hartstone-Rose|first4=A|year=2023|title=The roar of Rancho La Brea? Comparative anatomy of modern and fossil felid hyoid bones|journal=Journal of Morphology|volume=284|issue=10|page=e21627|doi=10.1002/jmor.21627|pmid=37708512 |s2cid=261090355 |doi-access=free}}</ref>