Smilodon (pronounced /ˈsmаɪlədɒn/), often called saber-toothed cat or saber-toothed tiger, is an extinct genus of the subfamily machairodontine saber-toothed cats endemic to North America and South America living from the Early Pleistocene through Lujanian stage of the Pleistocene epoch (1.8 mya—10,000 years ago), existing for approximately 1.790 million years

A number of Smilodon species have been described, but today usually only three are recognized.[2]

Smilodon neogaeus/populator skeleton
Smilodon gracilis, 2.5 million-500,000 years ago; the smallest and earliest species (estimated to have been only 55 to 170 kg (120 to 370 lb))[3] was the successor of Megantereon in North America, from which it probably evolved. The other Smilodon species probably derived from this species.
Smilodon fatalis, 1.6 million-10,000 years ago, replaced Smilodon gracilis in North America and western South America. In size it was between Smilodon gracilis and Smilodon populator, and about the same as the largest surviving cat, the Siberian Tiger. This species is estimated to have ranged from 250 to 360 kg (550 to 790 lb).[3] Sometimes two additional species are recognized, Smilodon californicus and Smilodon floridus, but usually they are considered to be subspecies of Smilodon fatalis.
Smilodon populator, 1 million-10,000 years ago; occurred in the eastern parts of South America and was the largest species of all machairodonts. It was 1.2 m (47 in) tall, 2.1 m (83 in) long on average and had a 30 cm (12 in) tail. With an estimated weight of 400 kg (880 lb), it was among the heaviest known felids.[3] Its upper canines reached 28 cm (11 in) and protruded up to 17 cm (6.7 in) out of the upper jaw.