Smilodon

The nickname "saber-tooth" refers to the extreme length of their maxillary canines. Despite the colloquial name "saber-toothed tiger", Smilodon is not closely related to the tiger (or any other living felid); the latter belongs to subfamily Pantherinae, whereas Smilodon belongs to subfamily Machairodontinae. The name Smilodon comes from Greek: σμίλη, (smilē), "carving knife"[3] + ὀδoύς (odoús), "tooth", or in the genitive: ὀδoύς, ὀδόντος, odóntos.[4]

The genus Smilodon was described by the Danish naturalist and palaeontologist Peter Wilhelm Lund in 1841. He found the fossils of Smilodon populator in caves near the small town of Lagoa Santa, in the state of Minas Gerais, Brazil. A number of Smilodon species have been described, but today usually only three are recognized.[5] Genetic evidence suggests the members of the genus diverged from the main lineage of modern cats (subfamily Felinae) around 14-18 million years ago.[6] Smilodon probably preyed on a wide variety of large game including bison, tapirs, deer, American camels, horses and ground sloths. As it is known for the saber-toothed cat Homotherium, Smilodon might have also killed juvenile mastodons and mammoths. Smilodon may also have attacked prehistoric humans, although this is not known for certain. The La Brea tar pits in California trapped hundreds of Smilodon in the tar, possibly as they tried to feed on mammoths already trapped. The Natural History Museum of Los Angeles County has many of their complete skeletons.
 * Smilodon gracilis, 2.5 million-500,000 years ago; the smallest and earliest species, estimated at 55 to 100 kg (120 to 220 lb) in weight[7] 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 invaded western South America as part of the Great American Interchange. Matching the largest living cat, the Siberian tiger in size, it ranged from 160 to 280 kg (350 to 620 lb).[7] Sometimes two additional species are recognized, Smilodon californicus and Smilodon floridanus, 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 it was perhaps the largest known felid with a body mass range of 220 to 360 kg (490 to 790 lb)[7] [8] possessing a massive chest and front legs, It was more than 1.40 m (55 in) high at the shoulder, 2.6 m (100 in) long on average and had a 30 cm (12 in) tail. Its upper canines reached 30 cm (12 in) and protruded up to 17 cm (6.7 in) out of the upper jaw

All info from Wkipedia