Anachlysictis

Anachlysictis; Temporal range:Mid Miocene(Laventan); ~13.8–11.8Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Theholotypelower jaw
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Sparassodonta
Family:	†Thylacosmilidae
Genus:	†Anachlysictis; Goin, 1997
Species:	†A. gracilis
Binomial name
	†Anachlysictis gracilis; Goin, 1997

Anachlysictis gracilisis anextinctcarnivorousmammalbelonging to the groupSparassodonta,which weremetatherians(a group includingmarsupialsand their close relatives) that inhabitedSouth Americaduring theCenozoic.Anachlysictisis the first record of such borhyaenoids in northernSouth America,and also the most primitive known member of the familyThylacosmilidae,a group of predators equipped with "saber teeth". It was also the only confirmed record of a thylacosmilid that did not belong to the genusThylacosmilusuntil the official publication ofPatagosmilusin 2010.^[1]

This species was found in theVillavieja Formationin the area ofLa VentainColombia,a famous fossil deposit in theMiddle Miocene(Laventan;13.8–11.8 million years ago),^[2]based on fragments that include a front portion of the lowerjaw,with an incipient molar tooth and a piece of carnassial from the front of the maxilla.^[3]

Description

Anachlysictis,was smaller than its better-known relativeThylacosmilus,weighing around 18 kilograms (40 lb).^[4]The specialized features ofThylacosmilussuch as the flanges on the lower jaw, were smaller (due to the upper canines not being proportionately as long). It also lacked a rim around the eye socket, resulting in a more flattened shape of theskull.Otherwise theiranatomywas not as specialized as that of later relatives. It hadcarnassialteeth to effectively process meat and flat fangs, located just below the nose, that were not cross-rounded as in unspecialized mammal carnivores, while the accommodation area of themassetermuscle (involved in the movements of the jaw) was reduced.^[5]This is because, as in other predatory saber-toothed species, this muscle is reduced, leaving more space for the jaw joint to increase its opening angle and letting the well-developed neck muscles bring down the skull and allow the fangs to bite into the flesh of their prey.^{[citation needed]}

Taxonomy

Until the discovery ofAnachlysictis,it was supposed thatThylacosmiluswas a close relative of the familyBorhyaenidae,or even a specialized member of the same, having emerged in the LateMiocene.The primitive characteristics and age ofAnachlysictissuggest an earlier origin of the thylacosmilids at the base of the superfamilyBorhyaenoidea,whosemonophylyneeds review. The pattern of the molars ofAnachlysictisis very similar to that of the little-known methatherianHondadelphys,also from theHonda Groupat theKonzentrat-Lagerstätte La Venta.This was originally considered to be a species ofopossum,but is now considered a primitivesparassodont,soHondadelphyscould well represent the sister clade of Thylacosmilidae.^[5]

References

^Forasiepi A. & Carlini A. A new thylacosmilid (Mammalia, Metatheria, Sparassodonta) from the Miocene ofPatagonia,Argentina.Zootaxa2552: 55–68 (2010)
^Anachlysictis gracilisatFossilworks.org
^Goin, F. J. (1997). New clues for understandingNeogenemarsupialradiations.In:Vertebrate Paleontology in the Neotropics. The Miocene Fauna of La Venta, Colombia,R. F. Kay, R. Cifelli, R. H. Madden, and J. Flynn, eds., pp. 185-204, Smithsonian Institution Press, Washington, DC.
^Wroe, S., Argot, C., & Dickman, C. (2004).On the rarity of big fierce carnivores and primacy of isolation and area: tracking large mammalian carnivore diversity on two isolated continents.Proceedings of the Royal Society B Biological Sciences,271(1544), 1203-1211.
^^a ^bGoin, F.J. 2003. Early marsupial radiations in South America. En: M. Jones, C. Dickman y M. Archer (eds.),Predators with Pouches, The Biology of Carnivorous Marsupials,CSIRO Publishing, Australia, pp. 30–42.

External links

Marsupial 'bears' and marsupial sabre-tooths in Tetrapod Zoology

[1] Forasiepi A. & Carlini A. A new thylacosmilid (Mammalia, Metatheria, Sparassodonta) from the Miocene ofPatagonia,Argentina.Zootaxa2552: 55–68 (2010)

[FWAnachlysictisGracilis-2] Anachlysictis gracilisatFossilworks.org

[3] Goin, F. J. (1997). New clues for understandingNeogenemarsupialradiations.In:Vertebrate Paleontology in the Neotropics. The Miocene Fauna of La Venta, Colombia,R. F. Kay, R. Cifelli, R. H. Madden, and J. Flynn, eds., pp. 185-204, Smithsonian Institution Press, Washington, DC.

[4] Wroe, S., Argot, C., & Dickman, C. (2004).On the rarity of big fierce carnivores and primacy of isolation and area: tracking large mammalian carnivore diversity on two isolated continents.Proceedings of the Royal Society B Biological Sciences,271(1544), 1203-1211.

[Goin,_2003-5] Goin, F.J. 2003. Early marsupial radiations in South America. En: M. Jones, C. Dickman y M. Archer (eds.),Predators with Pouches, The Biology of Carnivorous Marsupials,CSIRO Publishing, Australia, pp. 30–42.

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