Saber-toothed cat

An artists reconstruction of a Smilodon

A Smilodon skull on display at the American Museum of NaturalHistory

A saber-toothed cat (alternatively spelled sabre-toothed cat),[1] also misleadingly known as a saber-toothed tiger,[2][3] is any of various groups of preda-tory mammals related to modern cats (or resemblingcats) that were characterized by long, curved saber-

shaped canine teeth. These animals belong to taxaof Machairodontinae (Felidae), Barbourofelidae andNimravidae (both Feliformia), as well as two families re-lated to marsupials that were found worldwide from theEocene epoch to the end of the Pleistocene epoch (42mya 11,000 years ago), existing for about 42 millionyears.[4][5][6] The large maxillary canine teeth extendedfrom the mouth even when it was closed. Despite thename, not all animals known as saber-toothed cats wereclosely related to modern felines.The Nimravidae are the oldest, entering the landscapearound 42 mya and becoming extinct by 7.2 mya. Bar-bourofelidae entered around 16.9 mya and were extinctby 9 mya. These two would have shared some habitats.

1 Morphology

These subfamilies evolved their saber-toothed character-istics entirely independently. They are most known forhaving maxillary canines which were, in some species,up to 50 cm (19.7 inches) long and extended down fromthe mouth even when the mouth was closed. Sabre-toothed cats were generally more robust than todays catsand were quite bear-like in build. They were believed tobe excellent hunters and hunted animals such as sloths,mammoths, and other large prey. Evidence from thenumbers found at La Brea Tar Pits suggests that Smilodon,like modern lions, was a social carnivore.[7]

The rst late saber-tooth instance is a group of animalsancestral to mammals but not yet mammals. Known assynapsids or mammal-like reptiles, they were one of therst groups of animals to experience specialization ofteeth and many had long canines. Some had two pairs ofupper canines with two jutting down from each side, butmost had one pair of upper extreme canines. Because oftheir primitiveness, they are extremely easy to tell frommachairodonts. With no cononoid process, many sharppremolars more like pegs than scissors and a very long,lizard-like head are among several characteristics thatmark them out.The second appearance of long canines is Thylacosmilus,which is the most distinctive of the saber-tooth mammalsand is also easy to tell apart. It diers frommachairodontsin a possessing a very prominent ange and a tooth thatis triangular in cross section. The root of the canines ismore prominent than in machairodonts and a true sagittalcrest is absent.

1

2 3 ECOLOGY

The third instance of saber teeth is from order Creodonta.The small and slender Machaeroides bore canines thatwere thinner than in the average machairodont. Its muz-zle was longer and narrower.The fourth saber-tooth appearance is the ancient fam-ily of carnivores, the nimravids, and they are notoriouslyhard to tell apart from machairodonts. Both groups haveshort skulls, tall sagittal crests, and their general skullshape is very similar. Some have distinctive anges, andsome have none at all, so this confuses the matter fur-ther. Machairodonts were almost always bigger, though,and their canines were longer and more stout for the mostpart, but exceptions do appear.The fth appearance is the barbourofelids. These carni-vores are very closely related to actual cats, and as such,they are hard to tell apart. The best known barbourofelidis Barbourofelis, which diers from most machairodontsby a much heavier and more stout mandible, smallerorbits, massive and almost knobby anges, and caninesthat are farther back. The average machairodont hadwell-developed incisors, but barbourofelids were moreextreme.The sixth and last of the saber-tooth group to evolve werethe machairodonts themselves.

1st saber-tooth instance: Synapsida, thegorgonopsid Gorgonops skull

2nd saber-tooth instance: Thylacosmilidae(Sparassodonta) - Thylacosmilus atrox skull

3rd saber-tooth instance: Creodonta, family un-determined - Machaeroides skull

4th saber-tooth instance: Nimravidae (Carnivora)- Hoplophoneus primaevus skull and upper cervicalvertebrae

5th saber-tooth instance: Barbourofelidae(Carnivora) - Barbourofelis skeleton

6th saber-tooth instance: Felidae (Carnivora) -Smilodon skull and upper cervical vertebrae

2 Prey

Steps of reconstruction

Many of the saber-toothed cats food sources were largemammals such as elephants, rhinos, and other colossal

herbivores of the era. The evolution of enlarged caninesin Tertiary carnivores was a result of large mammals be-ing the source of prey for saber-toothed cats. The devel-opment of the saber-toothed condition appears to repre-sent a shift in function and killing behavior, rather thanone in predator-prey relations. Many hypotheses existconcerning saber-tooth killing methods, some of whichinclude attacking soft tissue such as the belly and throat,where biting deep was essential to generate killing blows.The elongated teeth also aided with strikes reaching ma-jor blood vessels in these large mammals. However, theprecise functional advantage of the saber-toothed catsbite, particularly in relation to prey size, is a mystery. Anew point-to-point bite model is introduced in the articleby Andersson et al., showing that for saber-tooth cats, thedepth of the killing bite decreases dramatically with in-creasing prey size. The extended gape of saber-toothedcats results in a considerable increase in bite depth whenbiting into prey with a radius of less than 10 cm. Forthe sabre-tooth, this size-reversed functional advantagesuggests predation on species within a similar size rangeto those attacked by present-day carnivorans, rather thanmega herbivores as previously believed.A disputing view of the cats hunting technique and abil-ity is presented by C.K. Brain in The Hunters or theHunted? in which he attributes the cats prey-killing abil-ities to its large neck muscles rather than its jaws. Largecats use both the upper and lower jaw to bite down andbring down the prey. The strong bite of the jaw is ac-credited to the strong temporalis muscle that attach fromthe skull to the coronoid process of the jaw. The largerthe coronoid process, the larger the muscle that attachesthere, so the stronger the bite. As C.K. Brain pointsout, the saber-toothed cats had a greatly reduced coro-noid process and therefore a disadvantageously weak bite.The cat did, however, have an enlarged mastoid process,a muscle attachment at the base of the skull, which at-taches to neck muscles. According to C.K. Brain, thesaber-tooth would use a downward thrust of the head,powered by the neck muscles to drive the large uppercanines into the prey. This technique was more ecientthan those of true cats.

3 EcologyThe similarity in all these unrelated families involves con-vergent evolution of the saber-like canines as a huntingadaptation. Meehan et al. note that it took around 8million years for a new type of saber-toothed cat to llthe niche of an extinct predecessor in a similar ecologicalrole; this has happened at least four times with dierentfamilies of animals developing this adaptation. Althoughthe adaptation of the saber-like canines made these crea-tures successful, it seems that the shift to obligate car-nivorism, alongwith co-evolutionwith large prey animals,led the saber-toothed cats of each time period to extinc-

3tion. As per Van Valkenburgh, the adaptations that madesaber-toothed cats successful also made the creatures vul-nerable to extinction. In her example, trends toward anincrease in size, along with greater specialization, actedas a macro-evolutionary ratchet": when large prey be-came scarce or extinct, these creatures would be unableto adapt to smaller prey or consume other sources of food,and would be unable to reduce their size so as to need lessfood.[8]

4 Saber-tooth genera

5 Saber-tooth evolutionary tree

6 References[1] See for example sabre-toothed cat Encyclopdia Bri-

tannica. 2009. Encyclopdia Britannica Online. 26 Oct.2009.

[2] Pool, Bob (September 16, 2012). What Is A Saber-tooth. UC Berkeley. Retrieved 2012-06-12. I remem-ber reading about this as a kid. I can still remember seeinga picture of the saber-toothed tiger struggling in the tar

[3] What Is a Sabertooth?". University of California Mu-seum of Paleontology. December 2005. Retrieved 2012-06-12. The name saber-toothed tiger is misleading asthese animals are not closely related to tigers.

[4] PaleoBiology Database: ''Smilodon'', basic info. Pale-odb.org. Retrieved 2012-09-06.

[5] PaleoBiology Database: ''Nimravidae'', basic info. Pa-leodb.org. Retrieved 2012-09-06.

[6] PaleoBiology Database: ''Barbourofelidae'', basic info.Paleodb.org. Retrieved 2012-09-06.

[7] Carbone, C.; Maddox, T.; Funston, P. J.; Mills, M. G.;Grether, G. F.; Van Valkenburgh, B. (2009). Parallelsbetween playbacks and Pleistocene tar seeps suggest so-ciality in an extinct sabretooth cat, Smilodon. Biol Lett. 5(1): 8185. doi:10.1098/rsbl.2008.0526. PMC 2657756.PMID 18957359.

[8] Van Valkenburgh, B. (2007). Deja vu: the evolu-tion of feeding morphologies in the Carnivora. In-tegrative and Comparative Biology 47 (1): 147163.doi:10.1093/icb/icm016.

7 Sources Andersson, K., Norman, D. and Werdelin, L.Sabretoothed Carnivores and the Killing of LargePrey. PloS ONE 6.10 (2011): 16. AcademicSearch Premier. Web. 11 Oct. 2012. http://dx.doi.org/10.1371/journal.pone.0024971

Brain, C. K. Part 2: Fossil Assemblages from theSterkfontein Valley Caves: Analysis and Interpreta-tion. The Hunters or the Hunted?: An Introductionto African Cave Taphonomy. Chicago: Universityof Chicago, 1981. N. pag. Print.

Meehan, T.J., Martin, L.D. Extinction and Re-Evolution of Similar Adaptive Types (Ecomorphs)in Cenozoic North American Ungulates and Carni-vores Reect van der Hammens Cycles. Natur-wissenschaften (2003) 90:131135. 07 Feb. 2003.http://dx.doi.org/10.1007/s00114-002-0392-1

Mol, D., W. v. Logchem, K. v. Hooijdonk, R.Bakker. The Saber-Toothed Cat. DrukWare, Norg2008. ISBN 978-90-78707-04-2.

Sardella, R. Web of Knowledge [v5.6]". SOCPALEONTOLOGICA ITALIANA, C/O E.SERPAGLI, EDITOR, IST DI PALEON-TOLOGIA VIA UNIV 4, MODENA, 00000,ITALY, 10 Mar. 2012. Web. 18 Oct. 2012..

Van Valkenburgh, B. Dj vu: The Evolution ofFeeding Morphologies in the Carnivora. Integra-tive and Comparative Biology. (2007) 47 1:147163. 22 May 2007. http://dx.doi.org/10.1093/icm016

8 Further reading Anton, Mauricio (2013). Sabertooth. Bloomington:Indiana University Press. ISBN 0253010497.

9 External links Extinct Cats Index Illinois State Museum: Saber-toothed Cats UC Berkeley Museum of Paleontology: Sabre-toothed Cats

Prehistoric cats and prehistoric cat-like creatures

4 10 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

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