Temporal range: Miocene–Pliocene
Thylacosmilus atrox and Glyptodon
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Metatheria
Order: Sparassodonta
Family: †Thylacosmilidae
Genus: Thylacosmilus
Riggs, 1933[1]

T. atrox
T. lentis

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Thylacosmilus ("pouch sabre") was a genus of sabre-toothed metatherian predators that first appeared during the Miocene. Remains of the animal have been found in parts of South America, primarily Argentina. Though Thylacosmilus is one of several predatory mammal genera typically called "sabre-toothed cats", it was not a felid but a sparassodont, a group closely related to marsupials, and only superficially resembled other sabre-toothed mammals due to convergent evolution.


Thylacosmilus had long, sabre-like upper canines and short, blunt, peg-like lower canines. The incisors were missing altogether and the other teeth were severely reduced, but, as distinct from machairodonts, their number was complete.[2][clarification needed] It is estimated to have weighed around 150 kilograms (330 lb).[3] Thylacosmilus and the similarly sized Marsupial Lion were the largest carnivorous metatherians.

Thylacosmilus lived in the warm grasslands middle and south South america. It likely eat medium to large sized animals like Macrauchenia, Toxodon, Homalodotherium and Eumegamys.

Thylacosmilus' sabre-teeth kept growing throughout its life, unlike those of true sabre-toothed felines. It also had a pair of elongated, scabbard-like flanges growing from the lower jaw, which protected the sabre-teeth when it closed its mouth. The cervical vertebrae were very strong and to some extent resembled the vertebrae of machairodonts.[2]

Thylacosmilus went extinct during the Pliocene, a timeframe closely corresponding to the arrival of the sabre-toothed cat Smilodon from North America in the Great American Interchange. Out-competition from the anatomically similar Smilodon appears to have driven the extinction, though this is not typical of other South American extinctions during the period.[4]


  1. ^ Riggs, E.C. 1934: A new marsupial saber-tooth from the Pliocene of Argentina and its relationships to other South American predacious marsupials. Transactions of the American Philosophical Society 24, 1–32.
  2. ^ a b Benes, Josef. Prehistoric Animals and Plants. Prague, Artua, 1979. Pg. 237-8
  3. ^ Sorkin, B. (2008-04-10). "A biomechanical constraint on body mass in terrestrial mammalian predators". Lethaia 41 (4): 333–347. doi:10.1111/j.1502-3931.2007.00091.x. Retrieved 2011-08-02. 
  4. ^ Kricher, John (1999). A Neotropical Companion: an Introduction to the Animals, Plants, and Ecosystems of the New World Tropics. Princeton University Press. pp. 114–115. Retrieved October 7, 2010. 
  • Evolution of the Earth by Donald R. Prothero, Jr., Robert H. Dott, Donald Prothero, and Jr., Robert Dott
  • The Earth Through Time by Harold L. Levin
  • Bringing Fossils To Life: An Introduction To Paleobiology by Donald R. Prothero

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