Editing Smilodon (section)

=== Evolution ===
[[File:Smilodon gracilis skull ANSP 44.1 (2).jpg|thumb|Partial skull of ''S. gracilis'', the earliest species in the [[genus]], [[Academy of Natural Sciences of Philadelphia]]]]
[[File:Smilodon californicus mount.jpg|thumb|right|''S. fatalis'' skeleton at [[National Museum of Natural History]]]]
[[File:Säbelzahnkatze, Tierpark Berlin, 500-606.jpg|thumb|right|''S. populator'' statue in [[Tierpark Berlin]] ]]
Long the most completely known [[Machairodontinae|saber-toothed cat]], ''Smilodon'' is still one of the best-known members of the group, to the point where the two concepts have been confused. The term [[Saber-toothed predator|''saber-tooth'']] itself refers to an [[ecomorph]] consisting of various groups of extinct predatory [[synapsid]]s (mammals and close relatives), which [[convergently evolved]] extremely long [[maxillary canine]]s, as well as adaptations to the skull and skeleton related to their use. This includes members of [[Gorgonopsia]], [[Thylacosmilidae]], [[Machaeroidinae]], [[Nimravidae]], [[Barbourofelidae]], and [[Machairodontinae]].{{Sfn|Antón|2013|pp=3–26}}<ref>{{cite journal |last1=Meehan |first1=T. J. |last2=Martin |first2=L. D. |year=2003 |title=Extinction and re-evolution of similar adaptive types (ecomorphs) in Cenozoic North American ungulates and carnivores reflect van der Hammen's cycles |journal=Die Naturwissenschaften |doi=10.1007/s00114-002-0392-1 |bibcode=2003NW.....90..131M|pmid=12649755 |volume=90 |issue=3 |pages=131–135 |s2cid=21117744 |url=https://www.researchgate.net/publication/10844456 }}</ref> Within the family [[Felidae]] (true cats), members of the [[subfamily]] [[Machairodontinae]] are referred to as saber-toothed cats, and this group is itself divided into three [[Tribe (biology)|tribes]]: [[Metailurini]] (false saber-tooths); [[Homotherini]] ([[scimitar]]-toothed cats); and [[Smilodontini]] ([[dirk]]-toothed cats), to which ''Smilodon'' belongs.{{Sfn|Antón|2013|pp=108–154}}

Members of Smilodontini are defined by their long slender canines with fine to no [[serration]]s, whereas Homotherini are typified by shorter, broad, and more flattened canines, with coarser serrations.{{Sfn|Antón|2013|pp=65–76}} Members of Metailurini were less specialized and had shorter, less flattened canines, and are not recognized as members of Machairodontinae by some researchers.{{Sfn|Antón|2013|pp=108–154}}

Despite the colloquial name "saber-toothed tiger", ''Smilodon'' is not closely related to the modern [[tiger]] (which belongs in the subfamily [[Pantherinae]]), or any other extant felid.<ref name="Berkeley">{{cite web |date=December 2005 |title=What Is a Sabertooth? |url=http://www.ucmp.berkeley.edu/mammal/carnivora/sabretooth.html |access-date=2012-06-12 |publisher=University of California Museum of Paleontology}}</ref> A 1992 ancient DNA analysis suggested that ''Smilodon'' should be grouped with modern cats (subfamilies [[Felinae]] and Pantherinae).<ref>{{cite journal |last1=Janczewski |first1=D. N. |last2=Yuhki |first2=N. |last3=Gilbert |first3=D. A. |last4=Jefferson |first4=G. T. |last5=O'Brien |first5=S. J. |year=1992 |title=Molecular phylogenetic inference from saber-toothed cat fossils of Rancho La Brea |journal=Proceedings of the National Academy of Sciences |volume=89 |issue=20 |pages=9769–9773 |bibcode=1992PNAS...89.9769J |doi=10.1073/pnas.89.20.9769 |pmc=50214 |pmid=1409696 |doi-access=free}}</ref> A 2005 study found that ''Smilodon'' belonged to a separate lineage.<ref name="Barnett">{{cite journal |last1=Barnett |first1=R. |last2=Barnes |first2=I. |last3=Phillips |first3=M. J. |last4=Martin |first4=L. D. |last5=Harington |first5=C. R. |last6=Leonard |first6=J. A. |last7=Cooper |first7=A. |year=2005 |title=Evolution of the extinct sabretooths and the American cheetah-like cat |journal=Current Biology |volume=15 |issue=15 |pages=R589–R590 |bibcode=2005CBio...15.R589B |doi=10.1016/j.cub.2005.07.052 |pmid=16085477 |s2cid=17665121 |doi-access=free}}</ref> A study published in 2006 confirmed this, showing that the Machairodontinae [[Speciation|diverged]] early from the ancestors of living cats and were not closely related to any living species.<ref>{{cite journal |last1=van den Hoek Ostende |first1=L. W. |last2=Morlo |first2=M. |last3=Nagel |first3=D. |year=2006 |title=Majestic killers: the sabre-toothed cats (Fossils explained 52) |journal=Geology Today |volume=22 |issue=4 |pages=150–157 |doi=10.1111/j.1365-2451.2006.00572.x |s2cid=128960196}}</ref> The ancestors of living cats and Machairodontinae estimated to have diverged around 20 million years ago.<ref name="Paijmans2017" /> The following [[cladogram]] based on fossils and DNA analysis shows the placement of ''Smilodon'' among extinct and extant felids, after Rincón and colleagues, 2011:<ref name="Rincón2011">{{cite journal |last1=Rincón |first1=A. |last2=Prevosti |first2=F. |last3=Parra |first3=G. |year=2011 |title=New saber-toothed cat records (Felidae: Machairodontinae) for the Pleistocene of Venezuela, and the Great American Biotic Interchange |journal=Journal of Vertebrate Paleontology |volume=31 |issue=2 |pages=468–478 |bibcode=2011JVPal..31..468R |doi=10.1080/02724634.2011.550366 |jstor=25835839 |s2cid=129693331 |hdl-access=free |hdl=11336/69016}}</ref>

{{clade| style=font-size:85%; line-height:85%
|label1=[[Felidae]]
|1={{clade
 |1=''[[Proailurus]]''
 |2={{clade
  |1=''[[Pseudaelurus]]''
  |2={{clade
   |1={{clade
   |label1=[[Pantherinae]]
   |1=''[[Panthera]]'' (tigers, lions, jaguars, and leopards)[[File:Lydekker - Leopard (white background).JPG|70 px]]
   |label2=[[Felinae]]
    |2={{clade
     |1=''[[Caracal (genus)|Caracal]]''[[File:Felis caracal - 1818-1842 - Print - Iconographia Zoologica - Special Collections University of Amsterdam -(White Background).jpg|50 px]]
     |2={{clade
      |1=''[[Leopardus]]'' ([[ocelot]] and relatives)[[File:Felis pardalis - 1834 - Print - Iconographia Zoologica - Special Collections University of Amsterdam -(White Background).jpg|50px]]
      |2={{clade
       |1=''[[Felis]]'' ([[domestic cats]] and relatives)[[File:Felis chaus - 1700-1880 - Print - Iconographia Zoologica - Special Collections University of Amsterdam -(White Background).jpg|50px]]
       |2={{clade
        |1=''[[Herpailurus]]'' (jaguarundi) [[File:Lydekker - Eyra White background.jpg|45 px]]
        |2={{clade
         |1=''[[Miracinonyx]]'' [[File:Miracinonyx inexpectatus.jpg|55 px]]
         |2=''[[Puma (genus)|Puma]]'' (cougar)[[File:Felis concolor - 1818-1842 - Print - Iconographia Zoologica - Special Collections University of Amsterdam -(white background).jpg|65 px]]}} }} }} }} }} }}
  |label2=[[Machairodontinae]]
   |2={{clade
    |1=''[[Dinofelis]]'' [[File:Dinofelis15DB.jpg|70 px]]
    |2={{clade
     |1={{clade
      |1=''[[Nimravides]]''
      |2={{clade
       |1=''[[Machairodus]]'' [[File:Machairodus from Cerro de Batallones.png|50 px]]
       |2={{clade
        |1=''[[Homotherium]]''<span style="{{MirrorH}}">[[File:Homotherium_life_reconstruction.png|55 px]]</span>
        |2=''[[Xenosmilus]]''<span style="{{MirrorH}}">[[File:Xenosmilus with concealed canine.jpg|60 px]]</span> }} }} }}
     |2={{clade
      |1=''[[Paramachairodus]]''
      |2={{clade
       |1=''[[Megantereon]]''
|label2='''''Smilodon'''''
       |2={{clade
        |1='''''Smilodon gracilis'''''<span style="{{MirrorH}}">[[File:Saber Toothed Tiger (PSF).png|55 px]]</span>
        |2={{clade
         |1='''''Smilodon populator'''''[[File:Smilodon pop2 15.jpg|67 px]]
         |2='''''Smilodon fatalis'''''[[File:Smilodon fatalis Knight (white background).jpg|67 px]] }} }} }} }} }} }} }} }} }} }}

The earliest felids are known from the [[Oligocene]] of Europe, such as ''[[Proailurus]]'', and the earliest one with saber-tooth features is the [[Miocene]] genus ''[[Pseudaelurus]]''.{{Sfn|Antón|2013|pp=108–154}} The skull and mandible morphology of the earliest saber-toothed cats was similar to that of the modern [[Neofelis|clouded leopards]] (''Neofelis''). The lineage further adapted to the precision killing of large animals by developing elongated canine teeth and wider gapes, in the process sacrificing high [[Bite force quotient|bite force]].<ref>{{cite journal |last=Christiansen |first=P. |year=2008 |title=Evolution of skull and mandible shape in cats (Carnivora: Felidae) |journal=PLOS ONE |doi=10.1371/journal.pone.0002807 |pmid=18665225 |pmc=2475670 |bibcode=2008PLoSO...3.2807C |volume=3 |issue=7 |page=e2807|doi-access=free }} {{open access}}</ref> As their canines became longer, the bodies of the cats became more robust for immobilizing prey.{{Sfn|Antón|2013|pp=65–76}} In [[Autapomorphy|derived]] smilodontins and homotherins, the [[lumbar]] region of the spine and the tail became shortened, as did the hind limbs.{{Sfn|Antón|2013|pp=108–154}} Machairodonts once represented a dominant group of felids distributed across Africa, Eurasia and the North America during the Miocene and Pliocene epochs,<ref>{{Cite journal |last=Christiansen |first=Per |date=October 2010 |title=Phylogeny of the sabertoothed felids ( Carnivora: Felidae: Machairodontinae) |url=https://onlinelibrary.wiley.com/doi/10.1111/cla.12008 |journal=Cladistics |language=en |volume=29 |issue=5 |pages=543–559 |doi=10.1111/cla.12008 |pmid=34814379 |issn=0748-3007}}</ref> but progressively declined over the course of the Pleistocene,<ref>{{Cite journal |last1=Piras |first1=Paolo |last2=Silvestro |first2=Daniele |last3=Carotenuto |first3=Francesco |last4=Castiglione |first4=Silvia |last5=Kotsakis |first5=Anastassios |last6=Maiorino |first6=Leonardo |last7=Melchionna |first7=Marina |last8=Mondanaro |first8=Alessandro |last9=Sansalone |first9=Gabriele |last10=Serio |first10=Carmela |last11=Vero |first11=Veronica Anna |last12=Raia |first12=Pasquale |date=May 2018 |title=Evolution of the sabertooth mandible: A deadly ecomorphological specialization |url=https://linkinghub.elsevier.com/retrieve/pii/S0031018217310465 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=496 |pages=166–174 |doi=10.1016/j.palaeo.2018.01.034|bibcode=2018PPP...496..166P |hdl=2158/1268434 |hdl-access=free }}</ref> by the [[Late Pleistocene]], only two genera of machairodonts remained, ''Smilodon'', and the distantly related ''[[Homotherium]]'', both largely confined to the Americas. Based on [[mitochondrial DNA]] sequences [[Ancient DNA|extracted from ancient bones]], the lineages of ''Homotherium'' and ''Smilodon'' are estimated to have diverged about 18 million years ago.<ref name="Paijmans2017">{{cite journal|last1= Paijmans|first1=J. L. A.|last2= Barnett|first2= R.|last3= Gilbert|first3=M. T. P.|last4= Zepeda-Mendoza|first4=M. L.|last5= Reumer|first5=J. W. F.|last6=de Vos|first6= J.|last7= Zazula|first7= G.|last8= Nagel|first8= D.|last9= Baryshnikov|first9=G. F.|last10= Leonard|first10=J. A.|last11= Rohland|first11= N.|last12 =Westbury|first12=M. V.|last13= Barlow|first13= A.|last14= Hofreiter|first14= M.|title= Evolutionary History of Saber-Toothed Cats Based on Ancient Mitogenomics|journal= Current Biology|volume=27|issue=21|pages=3330–3336.e5|date= 2017-10-19|doi= 10.1016/j.cub.2017.09.033|pmid=29056454|doi-access= free|bibcode=2017CBio...27E3330P }}</ref>

The earliest species of ''Smilodon'' is ''S.&nbsp;gracilis'', which existed from 2.5 [[Mya (unit)|million]] to 500,000 years ago (early [[Blancan]] to [[Irvingtonian]] ages) and was the successor in North America of ''Megantereon'', from which it probably evolved. ''Megantereon'' itself had entered North America from [[Eurasia]] during the [[Pliocene]], along with ''Homotherium''. ''S.&nbsp;gracilis'' reached the northern regions of South America in the [[Early Pleistocene]] as part of the [[Great American Interchange]].<ref name="Rincón2011" />{{Sfn|Antón|2013|pp=65–76}} ''S.&nbsp;fatalis'' existed 1.6 million–10,000 years ago (late Irvingtonian to [[Rancholabrean]] ages), and replaced ''S.&nbsp;gracilis'' in North America.<ref name=Kurten /> ''S.&nbsp;populator'' existed 1 million–10,000 years ago ([[Ensenadan]] to [[Lujanian]] ages); it occurred in the eastern parts of South America.<ref>{{cite journal |last1=de Castro |first1=Mariela Cordeiro |last2=Langer |first2=Max Cardoso |year=2008 |title=New postcranial remains of ''Smilodon populator'' Lund, 1842 from South-Central Brazil |journal=Revista Brasileira de Paleontologia |doi=10.4072/rbp.2008.3.06 |volume=11 |issue=3 |pages=199–206 |doi-access=free }}</ref>