Editing Smilodon (section)

=== 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>