Megantereon

Megantereon is an extinct genus of prehistoric machairodontine saber-toothed cat that lived in Eurasia, Africa and possibly North America from the late Pliocene to the Middle Pleistocene, first described by George Cuvier in 1824. It is a member of the tribe Smilodontini, and closely related to and possibly the ancestor of the more widely-known American sabertooth Smilodon, with which it shared greatly elongated saber canine teeth. In comparison to Smilodon, Megantereon was somewhat smaller, around the size of a jaguar, although it is thought to have had a similar hunting strategy as an ambush predator. Megantereon began to decline towards the end of the Early Pleistocene, becoming extinct in Africa first around 1.3 Ma and later in Europe around 1 Ma, surviving latest in East Asia into the Middle Pleistocene until sometime around 780-350,000 years ago. Environmental change, changes in prey availability, and competition from early humans have been suggested as reasons for its extinction.

==Taxonomy and evolution== left|thumb|upright|Teeth and jaw at the gallery of Paleontology and Comparative Anatomy, Paris.The type species of Megantereon, M. cultridens was described by Georges Cuvier in 1824, as Ursus cultridens, based on two teeth collected from Pliocene sediments in the Valdarno region of Tuscany, Italy, erroneously considering them to belong to a bear. In addition to the two teeth of Megantereon, Cuvier included another, much older tooth from the late Miocene of Eppelsheim in Germany in the species, which is now known to belong to the unrelated sabertooth cat Machairodus aphanistus. This decision would result in much later taxonomic confusion. In 1824, a fossil mandible of Megantereon from the Les Etouaires site in France was described by Croizet and Jobert as the new felid species Felis megantereon. As scientists were unfamiliar with the concept of sabertooths at the time, they did not realise that a large upper canine from the site belonged to the same species, instead attributing it to Cuvier's Ursus cultridens. In 1828, French paleontologist M. Bravard described a skull with preserved sabers from the Mont Perrier site in France as the species Megantereon megantereon. He suggested that Ursus cultridens should be renamed Machairodus cultridens and should be restricted to cats with serrated saberteeth (as is the case with the Eppelseim tooth, but not the unserrated teeth from Valdarno). However, in an 1890 review of sabertooth cat remains from Tuscany, Fabrini used the species name Machairodus (Meganthereon) cultridens to refer to cats which had unserrated canine saber teeth like those from Valdarno. There was much taxonomic confusion regarding the issue until 1979 when another review of sabertooth cats from Tuscany was carried out by G. Ficcarelli, who found that Megantereon crenatidens was the valid species according to nomenclatural rules for those sabertooths with unserrated sabers.