Thylacosmilus

Thylacosmilus is a extinct genus of carnivorous sparassodont.The Sparassodonta were actually not marsupials, but a sister group which used to be described as marsupials. found as fossils in deposits dated from about 10 million to 3 million years ago (late Miocene to late Pliocene epoch) in Argentina, South America. 

Thylacosmilus was sabre-toothed and was about as large as a modern jaguar. To a remarkable degree, Thylacosmilus paralleled the evolution of felid sabre-toothed cats like Smilodon. Its canine teeth were long and powerfully developed; they were used for stabbing prey. Its killing method was to hold its prey, and make deep bites into the soft tissue driven by powerful neck muscles. The canine teeth were protected by a well-developed flange, or projecting edge, in the chin region of the lower jaw. The canines continued to grow during adult life, which they do not in marsupials or placental mammals.Sparassodonts did not have the regular two-stage growth pattern of modern mammals.

Thylacosmilus died out during the late Pliocene, whereas saber-toothed cats did not get to South America until the middle Pleistocene epoch.see Great American Interchange.Prevosti, Francisco J; Forasiepi, Analia & Zimicz, Natalia 2013. The evolution of the Cenozoic terrestrial mammalian predator guild in South America: competition or replacement?. Journal of Mammalian Evolution 20: 3–21.  As a result, the last appearance of Thylacosmilus is separated from the first appearance of Smilodon by over one and a half million years.

 References 

category:Mammals of South America
category:Fossils
Category:Metatheria
Category:Saber-toothed cats