Classification and species

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.

1. Smilodon gracilis, 2.5 million-500,000 years ago; the smallest and earliest species (estimated to have been only 55 to 100 kg (120 to 220 lb) was the successor of Megantereon in North America, from which it probably evolved. The other Smilodon species probably derived from this species.
2. 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 was about 1m high at the shoulder and is estimated to have ranged from 160 to 280 kg (350 to 620 lb).^[3] Sometimes two additional species are recognized, Smilodon californicus and Smilodon floridanus, but usually they are considered to be subspecies of Smilodon fatalis.
3. 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 more than 1.22 m (48 in) high at the shoulder, 2.6 m (100 in) long on average and had a 30 cm (12 in) tail. With an estimated weight of 360 to 470 kg, and exceptionally large individuals estimated to have exceeded 500 kg^[4], it was among the heaviest known felids.^[3] Its upper canines reached 30 cm (12 in) and protruded up to 17 cm (6.7 in) out of the upper jaw.