Editing Smilodon (section)

== Paleobiology ==

=== Diet ===
[[File:Smilodon tooth.jpg|thumb|left|''S. populator'' [[canine tooth]]; the tip points to the right]]
An [[apex predator]], ''Smilodon'' primarily hunted large mammals. [[Isotope]]s preserved in the bones of ''S.&nbsp;fatalis'' in the La Brea Tar Pits reveal that [[ruminant]]s like bison (''[[Bison antiquus]]'', which was much larger than the modern [[American bison]]) and camels (''[[Camelops]]'') were most commonly taken by the cats there.<ref name=palaeoecology>{{cite journal|last1=Coltrain |first1=J. B. |last2=Harris |first2=J. M. |last3=Cerling |first3=T. E. |last4=Ehleringer |first4=J. R. |last5=Dearing |first5=M.-D. |last6=Ward |first6=J. |last7=Allen |first7=J. |year=2004 |title=Rancho La Brea stable isotope biogeochemistry and its implications for the palaeoecology of late Pleistocene, coastal southern California |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=205 |issue=3–4 |pages=199–219 |doi=10.1016/j.palaeo.2003.12.008 |url=http://bioweb.biology.utah.edu/dearing/2011/Publications/Stable_Isotopes/LaBrea_animals.pdf |archive-url=https://web.archive.org/web/20111111024742/http://bioweb.biology.utah.edu/dearing/2011/Publications/Stable_Isotopes/LaBrea_animals.pdf |archive-date=November 11, 2011 |url-status=dead |bibcode=2004PPP...205..199C }}</ref> 
''Smilodon fatalis'' may have also occasionally preyed upon ''[[Glyptotherium]]'', based on a skull from a juvenile ''Glyptotherium 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.{{sfn|Antón|2013|pp=203–204}} In addition, isotopes preserved in the [[tooth enamel]] of ''S.&nbsp;gracilis'' specimens from Florida show that this species fed on the [[peccary]] ''[[Platygonus]]'' and the [[llama]]-like ''[[Hemiauchenia]]''.<ref>{{cite journal|last=Feranec|first=R. S.|year=2005|title=Growth rate and duration of growth in the adult canine of ''S. gracilis'' and inferences on diet through stable isotope analysis|url=https://www.floridamuseum.ufl.edu/wp-content/uploads/sites/35/2017/03/bulletin-feraneclowres.pdf|journal=Bulletin of the Florida Museum of Natural History|volume=45|issue=4|pages=369–377|doi=10.58782/flmnh.psyo5090 |via=University of Florida}}</ref> 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.<ref>{{Cite journal |last1=Feranec |first1=Robert S. |last2=DeSantis |first2=Larisa R. G. |date=Summer 2014 |title=Understanding specifics in generalist diets of carnivorans by analyzing stable carbon isotope values in Pleistocene mammals of Florida |url=https://www.cambridge.org/core/journals/paleobiology/article/abs/understanding-specifics-in-generalist-diets-of-carnivorans-by-analyzing-stable-carbon-isotope-values-in-pleistocene-mammals-of-florida/7BAB33D0127FE87879C677F80F95808C |journal=[[Paleobiology (journal)|Paleobiology]] |language=en |volume=40 |issue=3 |pages=477–493 |doi=10.1666/13055 |bibcode=2014Pbio...40..477F |issn=0094-8373 |access-date=21 January 2024 |via=Cambridge Core}}</ref> Isotopic studies of [[dire wolf]] (''Aenocyon dirus'') and [[American lion]] (''Panthera atrox'') bones show an overlap with ''S.&nbsp;fatalis'' in prey, which suggests that they were competitors.<ref name=palaeoecology /> More detailed isotope analysis however, indicates that ''Smilodon fatalis'' preferred forest-dwelling prey such as tapirs, deer and forest-dwelling bison as opposed to the dire wolves' preferences for prey inhabiting open areas such as grassland.<ref>{{cite journal|first1=Larisa R. G. |last1=DeSantis|first2=Jonathan M. |last2=Crites|first3=Robert S. |last3=Feranec|first4=Kena |last4=Fox-Dobbs|first5=Aisling B. |last5=Farrell|first6=John M. |last6=Harris|first7=Gary T. |last7=Takeuchi|first8=Thure E. |last8=Cerling|year=2019|title=Causes and Consequences of Pleistocene Megafaunal Extinctions as Revealed from Rancho La Brea Mammals|journal=Current Biology|volume=29|issue=15|pages=2488–2495|doi=10.1016/j.cub.2019.06.059 |pmid=31386836|doi-access=free|bibcode=2019CBio...29E2488D }}</ref> The availability of prey in the [[La Brea Tar Pits|Rancho La Brea]] area was likely comparable to modern [[East Africa]].<ref>{{cite journal |last1=Vanvalkenburgh |first1=B. |last2=Hertel |first2=F. |year=1993 |title=Tough Times at La Brea: Tooth Breakage in Large Carnivores of the Late Pleistocene|journal=Science |pmid=17770024 |bibcode=1993Sci...261..456V |doi=10.1126/science.261.5120.456 |volume=261 |issue=5120 |pages=456–459|s2cid=39657617 }}</ref>

[[File:Smilodon stalking Palaeolama.jpg|thumb|Two ''S. populator'' stalking a ''[[Palaeolama|Palaeolama major]]'' group in Brazil, in a landscape also including the gomphothere ''[[Notiomastodon|Notiomastodon platensis]],'' the horse ''[[Equus neogeus]]'' and the ground sloth ''[[Catonyx|Catonyx cuvieri]]'']]
As ''Smilodon'' migrated to South America, its diet changed; bison were absent, the [[Equus (genus)|horses]] and [[proboscidea]]ns were different, and native ungulates such as [[toxodonts]] and [[litopterns]] were completely unfamiliar, yet ''S.&nbsp;populator'' thrived as well there as its relatives in North America.{{Sfn|Antón|2013|pp=65–76}} Isotopic analysis for ''S. populator'' suggests that its main prey species included the camel like litoptern ungulate ''[[Macrauchenia]]'',<ref name=":0">{{Cite journal |last1=Bocherens |first1=Hervé |last2=Cotte |first2=Martin |last3=Bonini |first3=Ricardo |last4=Scian |first4=Daniel |last5=Straccia |first5=Pablo |last6=Soibelzon |first6=Leopoldo |last7=Prevosti |first7=Francisco J. |date=May 2016 |title=Paleobiology of sabretooth cat Smilodon populator in the Pampean Region (Buenos Aires Province, Argentina) around the Last Glacial Maximum: Insights from carbon and nitrogen stable isotopes in bone collagen |url=https://linkinghub.elsevier.com/retrieve/pii/S0031018216000912 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=449 |pages=463–474 |bibcode=2016PPP...449..463B |doi=10.1016/j.palaeo.2016.02.017 |hdl=11336/43965|hdl-access=free }}</ref> the 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.<ref>{{Cite journal|last1=Dantas|first1=Mário André Trindade|last2=Cherkinsky|first2=Alexander|last3=Lessa|first3=Carlos Micael Bonfim|last4=Santos|first4=Luciano Vilaboim|last5=Cozzuol|first5=Mario Alberto|last6=Omena|first6=Érica Cavalcante|last7=Silva|first7=Jorge Luiz Lopes|last8=Sial|first8=Alcides Nóbrega|last9=Bocherens|first9=Hervé|date=2020-07-14|title=Isotopic paleoecology (δ13C, δ18O) of a late Pleistocene vertebrate community from the Brazilian Intertropical Region|journal=Revista Brasileira de Paleontologia|language=en|volume=23|issue=2|pages=138–152|doi=10.4072/rbp.2020.2.05|issn=2236-1715|doi-access=free}}</ref> Regressions suggests that a {{cvt|436|kg}} ''S. populator'' is capable of taking on prey up to {{cvt|3|tonnes}}.<ref name="LargeSkull2">{{cite journal |last1=Manzuetti |first1=A. |last2=Perea |first2=D. |last3=Jones |first3=W. |last4=Ubilla |first4=M. |last5=Rinderknecht |first5=A. |date=2020 |title=An extremely large saber-tooth cat skull from Uruguay (late Pleistocene–early Holocene, Dolores Formation): body size and paleobiological implications |url=https://www.academia.edu/73338127 |journal=Alcheringa: An Australasian Journal of Palaeontology |volume=44 |issue=2 |pages=332–339 |bibcode=2020Alch...44..332M |doi=10.1080/03115518.2019.1701080 |s2cid=216505747}}</ref>

The differences between the North and South American species may be due to the difference in prey between the two continents.<ref name="Kurten" /> ''Smilodon'' may have avoided eating bone and would have left enough food for scavengers.<ref>{{cite journal |last1=Van Valkenburgh |first1=B. |last2=Teaford |first2=M. F. |last3=Walker |first3=A. |year=1990 |title=Molar microwear and diet in large carnivores: inferences concerning diet in the sabretooth cat, ''Smilodon fatalis'' |journal=Journal of Zoology |doi=10.1111/j.1469-7998.1990.tb05680.x |volume=222 |issue=2 |pages=319–340 }}</ref> [[Coprolite]]s assigned to ''S. populator'' recovered from Argentina preserve [[osteoderms]] from the ground sloth ''[[Mylodon]]''  and a ''[[Lama (genus)|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.<ref>{{Cite journal |last1=Moreno Rodríguez |first1=Ana P. |last2=Chimento |first2=Nicolás R. |last3=Agnolín |first3=Federico L. |last4=Jofré |first4=Guillermo |last5=Gentil |first5=Adriel |title=A possible ''Smilodon'' (Mammalia, Felidae) Coprolite from the Pleistocene of Argentina |date=2022|url=https://www.researchgate.net/publication/362246133 |journal=PALAIOS |volume=37 |issue=7 |pages=402–410 |doi=10.2110/palo.2021.056 |bibcode=2022Palai..37..402M |s2cid=251078622 |issn=1938-5323}}</ref> Examinations of dental microwear from La Brea further suggests that ''Smilodon'' consumed both flesh and bone.<ref name=":1">{{Cite journal |last1=DeSantis |first1=Larisa R.G. |last2=Shaw |first2=Christopher A. |title=Sabertooth Cats with Toothaches: Impacts of Dental Injuries on Feeding Behavior in Late Pleistocene Smilodon Fatalis (Mammalia, Felidae) from Rancho la Brea (Los Angeles, California) |journal=Geological Society of America Abstracts with Programs |date=2018 |url=https://gsa.confex.com/gsa/2018AM/webprogram/Paper322567.html |page=322567 |doi=10.1130/abs/2018AM-322567|volume=50|issue=6}}</ref> ''Smilodon'' itself may have scavenged dire wolf kills.<ref>{{cite journal |last=Van Valkenburgh |first=B. |year=1991 |title=Iterative evolution of hypercarnivory in canids (Mammalia: Carnivora): evolutionary interactions among sympatric predators |journal=Paleobiology |jstor=2400749 |volume=17 |issue=4 |pages=340–362|doi=10.1017/S0094837300010691 |bibcode=1991Pbio...17..340V |s2cid=251052044 }}</ref> 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.{{Sfn|Antón|2013|pp=176–216}}[[File:Felipeda miramarensis huellas de smilodon.jpg|thumb|right|Tracks from Argentina which may have been produced by ''Smilodon'']]

=== Predatory behavior ===
The [[brain]] of ''Smilodon'' had [[Sulcus (neuroanatomy)|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 [[Cat senses#Sight|eyes]] that were not as forward-facing as those of modern cats, which have good [[binocular vision]] to help them move in trees.{{Sfn|Antón|2013|pp=176–216}} ''Smilodon'' was likely an [[ambush predator]] that concealed itself in dense vegetation, as its limb proportions were similar to modern forest-dwelling cats,<ref>{{cite journal |last=Gonyea |first=W. J. |year=1976 |title=Behavioral implications of saber-toothed felid morphology |journal=Paleobiology |jstor=2400172 |volume=2 |issue=4 |pages=332–342|doi=10.1017/S0094837300004966 |bibcode=1976Pbio....2..332G |s2cid=87481727 }}</ref> and its short tail would not have helped it balance while running.<ref name="Berkeley"/> 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.<ref name="Anton 2013">{{cite book |last=Anton |first=Mauricio |author-link=Mauricio Anton |date=2013 |title=Sabertooth}}</ref> Tracks from Argentina named ''Felipeda miramarensis'' in 2019 may have been produced by ''Smilodon''. If correctly identified, the tracks indicate that the animal had fully retractible claws, [[plantigrade]] feet, lacked strong [[supination]] capabilities in its paws, notably robust forelimbs compared to the hindlimbs, and was probably an ambush predator.<ref name="Tracks">{{cite journal |last1=Agnolin |first1=F. L. |last2=Chimento |first2=N. R. |last3=Campo |first3=D. H. |last4=Magnussen |first4=M. |last5=Boh |first5=D. |last6=De Cianni |first6=F. |title=Large Carnivore Footprints from the Late Pleistocene of Argentina |journal=Ichnos |date=2019 |volume=26 |issue=2 |pages=119–126 |doi=10.1080/10420940.2018.1479962|bibcode=2019Ichno..26..119A |s2cid=134190731 }}</ref>

The [[heel bone]] of ''Smilodon'' was fairly long, which suggests it was a good jumper.<ref name="Turner" /> Its well-developed flexor and extensor muscles in its [[forearm]]s probably enabled it to pull down, and securely hold down, large prey. Analysis of the cross-sections of ''S.&nbsp;fatalis'' [[humerus|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 humerus cortical wall in ''S. fatalis'' was a 15 % thicker than excpected in modern big cats of similar size. The thickening of ''S.&nbsp;fatalis'' [[femur]]s was within the range of extant felids.<ref name=forelimbs>{{cite journal |last1=Meachen-Samuels |first1=J. A. |last2=Van Valkenburgh |first2=B. |year=2010 |title=Radiographs reveal exceptional forelimb strength in the sabertooth cat, ''Smilodon fatalis'' |journal=PLOS ONE |issn=1932-6203 |doi=10.1371/journal.pone.0011412 |pmid=20625398 |pmc=2896400 |volume=5 |issue=7 |pages=e11412|bibcode=2010PLoSO...511412M |doi-access=free }} {{open access}}</ref><ref>{{Cite journal |last=Krishnaswamy |first=Dolly J. |date=2 July 2010 |title=ScienceShot: Saber-tooth Tigers Add Powerful Arms to Their Arsenal |url=https://www.science.org/content/article/scienceshot-saber-tooth-tigers-add-powerful-arms-their-arsenal |journal=Science}}</ref>  Its canines 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.<ref name=forelimbs /> 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.<ref name="Anton 2013" /> The bending force applied from the back to front of a ''S. fatalis'' upper canine required to break it, has been estimated to be of 7000 [[Newton (unit)|Newtons]], in comparison, in lions and tigers, two predators of similar size, a bending force of 8243 and 7440 Newtons, respectively, would be required.<ref>{{Cite journal |last=Freeman |first=P. W. |last2=Lemen |first2=C. |date=2007 |title=An experimental approach to modeling the strength of canine teeth |url=https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1012&context=natrespapers |journal=Journal of Zoology |language=en |volume=271 |issue=2 |pages=162–169 |doi=10.1111/j.1469-7998.2006.00194.x |issn=1469-7998}}</ref>

[[File:Smilodon bite.png|thumb|left|Maximum gape of a [[saber-toothed cat]] (A) and reconstructions of neck bite in prey of different sizes (B, C)]]

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.<ref name=forelimbs /><ref>{{cite journal |last1=McHenry |first1=C. R. |last2=Wroe |first2=S. |last3=Clausen |first3=P. D. |last4=Moreno |first4=K. |last5=Cunningham |first5=E. |year=2007 |title=Supermodeled sabercat, predatory behavior in ''Smilodon fatalis'' revealed by high-resolution 3D computer simulation |journal=PNAS |doi=10.1073/pnas.0706086104 |pmid=17911253 |pmc=2042153 |bibcode=2007PNAS..10416010M |volume=104 |issue=41 |pages=16010–16015 |doi-access=free }}</ref> 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.<ref>{{cite journal |last=Anyonge |first=W. |year=1996 |title=Microwear on canines and killing behavior in large carnivores: saber function in ''Smilodon fatalis'' |journal=Journal of Mammalogy |doi=10.2307/1382786 |jstor=1382786 |volume=77 |issue=4 |pages=1059–1067 |doi-access=free }}</ref> 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.<ref>{{cite journal|last1=Figueirido|first1=B.|last2=Lautenschlager|first2=S.|last3=Pérez-Ramos|first3=A.|last4=Van Valkenburgh|first4=B.|year=2018|title=Distinct Predatory Behaviors in Scimitar- and Dirk-Toothed Sabertooth Cats|journal=Current Biology|volume=28|issue=20|pages=3260–3266.e3|doi=10.1016/j.cub.2018.08.012|pmid=30293717|doi-access=free|bibcode=2018CBio...28E3260F |hdl=10630/29727|hdl-access=free}}</ref> The mandibular flanges may have helped resist bending forces when the mandible was pulled against the hide of a prey animal.<ref name="Brown2014">{{cite journal |last1=Brown |first1=J. G. |year=2014 |title=Jaw function in ''Smilodon fatalis'': a reevaluation of the canine shear-bite and a proposal for a new forelimb-powered class 1 lever model |journal=PLOS ONE |issn=1932-6203 |doi=10.1371/journal.pone.0107456 |pmid=25272032 |pmc=4182664 |volume=9 |issue=10 |pages=e107456|bibcode=2014PLoSO...9j7456B |doi-access=free }} {{open access}}</ref> 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.<ref>{{Cite book |last=Wheeler |first=H. Todd |title=The Other Saber-tooths: Scimitar-tooth Cats of the Western Hemisphere |publisher=Johns Hopkins University Press |year=2011 |editor-last=L. Naples |editor-first=Virginia |pages=19–35 |chapter=Experimental Paleontolgy of the Scimitar-tooth and Dirk-tooth Killing Bites |editor-last2=D. Martin |editor-first2=Larry |editor-last3=P. Babiarz |editor-first3=John |chapter-url=https://www.academia.edu/6463625}}</ref>

{{multiple image |align = right |total_width = 350
|image1 = Smilodon maximum gape.jpg
|alt1 =
|image2 = Smilodon gaping.jpg 
|alt2 =
|footer = ''S. fatalis'' skull with muscle reconstruction showing maximum gape (left) and restoration by [[Mauricio 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.{{Sfn|Antón|2013|pp=176–216}} 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.<ref name="Anton" /> A study published in 2022 of how machairodonts fed revealed that wear patterns on the teeth of ''S. fatalis'' also suggest that it was capable of eating bone to a similar extent as lions. This and comparisons with bite marks left by the contemporary machairodont ''[[Xenosmilus]]'' suggest that ''Smilodon'' and its relatives could efficiently de-flesh a carcass of meat when feeding without being hindered by their long canines.<ref name="carcassconsumption">{{cite journal |last1=Domínguez-Rodrigo |first1=Manuel |last2=Egeland |first2=Charles P. |last3=Cobo-Sánchez |first3=Lucía |last4=Baquedano |first4=Enrique |last5=Hulbert |first5=Richard C. |title=Sabertooth carcass consumption behavior and the dynamics of Pleistocene large carnivoran guilds |journal=Scientific Reports |date=2022 |volume=12 |issue=1 |pages=6045 |doi=10.1038/s41598-022-09480-7| pmid=35501323|pmc=9061710 |bibcode=2022NatSR..12.6045D }}</ref>

Despite being more powerfully built than other large cats, ''Smilodon'' had a weaker bite. Modern big cats have more pronounced [[zygomatic arch]]es, while these were smaller in ''Smilodon'', which restricted the thickness and therefore power of the [[temporalis muscle]]s and thus reduced ''Smilodon''{{'}}s 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).<ref name="NewscientistOct2007">{{cite journal |last=Hecht |first=J. |date=1 October 2007 |title=Sabre-tooth cat had a surprisingly delicate bite |journal=New Scientist |url=https://www.newscientist.com/article/dn12712-sabretooth-cat-had-a-surprisingly-delicate-bite.html}}</ref><ref name="Wroe et al., 2004">{{cite journal |url=http://intern.forskning.no/dokumenter/wroe.pdf |author=Wroe, S. |author2=McHenry2, C. |author3=Thomason, J. |year=2004 |title=Bite club: comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa |journal=Proceedings of the Royal Society |volume=272 |issue=1563 |pages=619–25 |doi=10.1098/rspb.2004.2986 |pmid=15817436 |pmc=1564077 |url-status=dead |archive-url=https://web.archive.org/web/20130825231325/http://intern.forskning.no/dokumenter/wroe.pdf |archive-date=2013-08-25 }}</ref> There seems to be a general rule that the saber-toothed cats with the largest canines had proportionally weaker bites. Analyses of canine [[Flexural strength|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.<ref>{{cite journal |last=Christiansen |first=P. |year=2007 |title=Comparative bite forces and canine bending strength in feline and sabretooth felids: implications for predatory ecology |journal=Zoological Journal of the Linnean Society |doi=10.1111/j.1096-3642.2007.00321.x |volume=151 |issue=2 |pages=423–437 |doi-access=free }}</ref> In addition, ''Smilodon''{{'s}} gape could have reached over 110 degrees,<ref>{{cite journal |last1=Andersson |first1=K. |last2=Norman |first2=D. |last3=Werdelin |first3=L. |year=2011 |title=Sabretoothed carnivores and the killing of large prey |journal=PLOS ONE |doi=10.1371/journal.pone.0024971 |bibcode=2011PLoSO...624971A |pmid=22039403 |pmc=3198467 |volume=6 |issue=10 |page=e24971|doi-access=free }} {{open access}}</ref> while that of the modern lion reaches 65 degrees.<ref>{{cite journal |last=Martin |first=L. D. |year=1980 |title=Functional morphology and the evolution of cats |journal=Transactions of the Nebraska Academy of Sciences |volume=8 |pages=141–154 |url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1286&context=tnas&sei-redir=1}}</ref> This made the gape wide enough to allow ''Smilodon'' to grasp large prey despite the long canines.<ref name="Anton" /> A 2018 study compared the killing behavior of ''Smilodon fatalis'' and ''Homotherium serum'', and found that the former had a strong skull with little [[trabecular bone]] for a stabbing canine-shear bite, whereas the latter had more trabecular bone and used a clamp and hold style more similar to lions. The two would therefore have held distinct ecological niches.<ref name="DistinctPredatoryBehaviors">{{cite journal |last1=Figueirido |first1=B. |last2=Lautenschlager |first2=S. |last3=Pérez-Ramos |first3=A. |last4=Van Valkenburgh |first4=B. |title=Distinct Predatory Behaviors in Scimitar- and Dirk-Toothed Sabertooth Cats |journal=Current Biology |date=2018 |volume=28 |issue=20 |pages=3260–3266.e3 |doi=10.1016/j.cub.2018.08.012|pmid=30293717 |url=https://research.birmingham.ac.uk/portal/en/publications/distinct-predatory-behaviors-in-scimitar-and-dirktoothed-sabertooth-cats(2f520864-4cce-4550-acf5-47c699b69100).html |doi-access=free |bibcode=2018CBio...28E3260F |hdl=10630/29727 |hdl-access=free }}</ref> The supplementary materials of a 2020 study suggested ''S. gracilis'' and ''S. populator'' had a jaw gape of 89.13 and 82.05 degrees respectively.<ref name="InoBite">{{cite journal |last1=Lautenschlager |first1=Stephan |last2=Figueirido |first2=Borja |last3=Cashmore |first3=Daniel D. |last4=Bendel |first4=Eva-Maria |last5=Stubbs |first5=Thomas L. |year=2020 |title=Morphological convergence obscures functional diversity in sabre-toothed carnivores |journal=[[Proceedings of the Royal Society B]] |volume=287 |issue=1935 |pages=1–10 |doi=10.1098/rspb.2020.1818 |issn=1471-2954 |pmc=7542828 |pmid=32993469 |doi-access=free}}</ref>

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 [[Cat|domestic cat]]. This indicates that ''S. fatalis'' used less olfaction for its daily activities than modern felids.<ref>{{Cite journal |last1=Bird |first1=Deborah J. |last2=Murphy |first2=William J. |last3=Fox-Rosales |first3=Lester |last4=Hamid |first4=Iman |last5=Eagle |first5=Robert A. |last6=Van Valkenburgh |first6=Blaire |date=2018 |title=Olfaction written in bone: cribriform plate size parallels olfactory receptor gene repertoires in Mammalia |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=285 |issue=1874 |pages=20180100 |doi=10.1098/rspb.2018.0100 |issn=0962-8452 |pmc=5879636 |pmid=29540522}}</ref>

=== Natural traps ===
[[File:Smilodon and Canis dirus.jpg|thumb|''S. fatalis'' fighting [[dire wolves]] 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<ref>{{cite journal|last1=Shaw|first1=Christopher A.|last2=Quinn|first2=James P.|title=The Addition of ''Smilodon fatalis'' (Mammalia: Carnivora: Felidae) to the Biota of the Late Pleistocene Carpinteria Asphalt Deposits in California, with Ontogenetic and Ecologic Implications for the Species|publisher=Natural History Museum of Los Angeles County|journal=Science Series 42: Contributions in Science |issue=A special volume entitled La Brea and Beyond: the Paleontology of Asphalt–Preserved Biotas in commemoration of the 100th anniversary of the Natural History Museum of Los Angeles County's excavations at Rancho La Brea|editor=John M. Harris|date=September 15, 2015|pages=91–95|url=https://tarpits.org/sites/default/files/blog_images/La%20Brea%20and%20Beyond%202015.%20NHM%20Science%20Science%20No.%2042.pdf|access-date=September 30, 2017|archive-url=https://web.archive.org/web/20161225011549/http://www.tarpits.org/sites/default/files/blog_images/La%20Brea%20and%20Beyond%202015.%20NHM%20Science%20Science%20No.%2042.pdf|archive-date=December 25, 2016|url-status=dead}}</ref> 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.{{Sfn|Antón|2013|pp=30–33}}

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.{{Sfn|Antón|2013|pp=30–33}}

=== 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>

=== Development ===
[[File:Smilodon canine replacement.jpg|thumb|Undersides of ''S. fatalis'' skulls, showing canine replacement, [[George C. Page Museum]]]]

''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 {{cvt|7|mm}} 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.<ref name="SD2015.07.01">{{cite web |date=2015-07-01 |title=Dagger-like canines of saber-toothed cats took years to grow |website=[[ScienceDaily]] |url=https://www.sciencedaily.com/releases/2015/07/150701151821.htm |access-date=2015-07-02 |archive-url=https://web.archive.org/web/20150702152240/https://www.sciencedaily.com/releases/2015/07/150701151821.htm |archive-date=2015-07-02}}</ref><ref name="Mihlbachler2015">{{cite journal |last1=Mihlbachler |first1=M. C. |last2=Wysocki |first2=M. A. |last3=Feranec |first3=R. S. |last4=Tseng |first4=Z. J. |last5=Bjornsson |first5=C. S. |date=2015-07-01 |title=Using a novel absolute ontogenetic age determination technique to calculate the timing of tooth eruption in the saber-toothed cat, ''Smilodon fatalis'' |journal=PLOS ONE |doi=10.1371/journal.pone.0129847 |pmid=26132165 |bibcode=2015PLoSO..1029847W |pmc=4489498 |volume=10 |issue=7 |pages=e0129847|doi-access=free }} {{open access}}</ref><ref>{{cite journal |last=Feranec |first=R. C. |year=2004 |title=Isotopic evidence of saber-tooth development, growth rate, and diet from the adult canine of ''Smilodon fatalis'' from Rancho La Brea |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |doi=10.1016/j.palaeo.2004.01.009 |volume=206 |issue=3–4 |pages=303–310|bibcode=2004PPP...206..303F }}</ref> 

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.<ref>{{cite journal |last1= Tseng |first1= Z.J. |date= April 2024 |title= Bending performance changes during prolonged canine eruption in saber-toothed carnivores: A case study of ''Smilodon fatalis'' |journal= The Anatomical Record |volume=  307 |issue= 5 |pages= |doi= 10.1002/ar.25447|doi-access= free |pmid= 38588019 }}</ref>

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.<ref>{{cite journal|last1=Long|first1=K.|last2=Prothero|first2=D.|last3=Madan|first3=M.|last4=Syverson|first4=V. J. P.|last5=Smith|first5=T.|title=Did saber-tooth kittens grow up musclebound? A study of postnatal limb bone allometry in felids from the Pleistocene of Rancho La Brea|journal=PLOS ONE|date=2017|volume=12|issue=9|pages=e0183175|doi=10.1371/journal.pone.0183175|pmid=28953899|pmc=5617143|bibcode=2017PLoSO..1283175L|doi-access=free}}</ref> 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.<ref name="Reynolds, Seymour, and Evans 2021">{{Cite journal|title=Smilodon fatalis siblings reveal life history in a saber-toothed cat|date=January 7, 2021|journal=iScience|pages=101916|doi=10.1016/j.isci.2020.101916|doi-access=free|last1=Reynolds|first1=Ashley R.|last2=Seymour|first2=Kevin L.|last3=Evans|first3=David C.|volume=24|issue=1|pmid=33532710|pmc=7835254|bibcode=2021iSci...24j1916R}}</ref>

=== Paleopathology ===

[[File:Smilodon subchondral defects.PNG|thumb|left|Large [[subchondral defects]] in ''S. fatalis'' limb-joints (arrows)]]
Several ''Smilodon'' fossils show signs of [[ankylosing spondylitis]], [[hyperostosis]] and trauma.<ref name="Bjorkengren">{{cite journal |last1=Bjorkengren |first1=A. G. |last2=Sartoris |first2=D. J. |last3=Shermis |first3=S. |last4=Resnick |first4=D. |year=1987 |title=Patterns of paravertebral ossification in the prehistoric saber-toothed cat |journal=American Journal of Roentgenology |pmid=3103404 |doi=10.2214/ajr.148.4.779 |volume=148 |issue=4 |pages=779–782|doi-access= }}</ref> One study of 1,000 ''Smilodon'' skulls found that 36% of them had eroded [[parietal bone]]s, 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.<ref>{{cite journal |last=Duckler |first=G. L. |year=1997 |title=Parietal depressions in skulls of the extinct saber-toothed felid ''Smilodon fatalis'': evidence of mechanical strain |journal=Journal of Vertebrate Paleontology |doi=10.1080/02724634.1997.10011006 |volume=17 |issue=3 |pages=600–609|bibcode=1997JVPal..17..600D }}</ref> 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.{{Sfn|Antón|2013|p=199}}

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.<ref>{{cite journal|last1=Brown|first1=C.|last2=Balisi|first2=M.|last3=Shaw|first3=C. A.|last4=Van Valkenburgh|first4=B.|title=Skeletal trauma reflects hunting behaviour in extinct sabre-tooth cats and dire wolves|journal=Nature Ecology & Evolution|date=2017|volume=1|issue=5|pages=0131|doi=10.1038/s41559-017-0131|pmid=28812696|bibcode=2017NatEE...1..131B |s2cid=8008808}}</ref> 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.<ref name="Subchondral defects">{{cite journal |last1=Schmökel |first1=Hugo |last2=Farrell |first2=Aisling |last3=Balisi |first3=Mairin F. |title=Subchondral defects resembling osteochondrosis dissecans in joint surfaces of the extinct saber-toothed cat ''Smilodon fatalis'' and dire wolf ''Aenocyon dirus'' |journal=PLOS ONE |date=2023 |volume=18 |issue=7 |pages=e0287656 |doi=10.1371/journal.pone.0287656|pmid=37436967 |pmc=10337945 |bibcode=2023PLoSO..1887656S |doi-access=free }}</ref>

[[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.<ref>{{Cite journal |last1=Luna |first1=Carlos A. |last2=Pool |first2=Roy R. |last3=Ercoli |first3=Marcos D. |last4=Chimento |first4=Nicolás R. |last5=Barbosa |first5=Fernando H. de S. |last6=Zurita |first6=Alfredo E. |last7=Cuaranta |first7=Pedro |date=22 May 2023 |title=Osteomyelitis in the manus of Smilodon populator (Felidae, Machairodontinae) from the Late Pleistocene of South America |url=https://www.sciencedirect.com/science/article/pii/S1871174X23000471 |journal=[[Palaeoworld]] |volume=33 |issue=2 |pages=517–525 |doi=10.1016/j.palwor.2023.05.001 |issn=1871-174X |access-date=5 February 2024 |via=Elsevier Science Direct}}</ref>