title: Smilodon
context: Fossils of Smilodon were discovered in North America from the second half of the 19th century onwards.[1] In 1869, American paleontologist Joseph Leidy described a maxilla fragment with a molar, which had been discovered in a petroleum bed in Hardin County, Texas. He referred the specimen to the genus Felis (which was then used for most cats, extant as well as extinct) but found it distinct enough to be part of its own subgenus, as F. (Trucifelis) fatalis.[5] The species name means "fate" or "destiny", but it is thought Leidy intended it to mean "fatal".[6] In an 1880 article about extinct American cats, American paleontologist Edward Drinker Cope pointed out that the F.fatalis molar was identical to that of Smilodon, and he proposed the new combination S.fatalis.[7] Most North American finds were scanty until excavations began in the La Brea Tar Pits in Los Angeles, where hundreds of individuals of S.fatalis have been found since 1875.[1] S.fatalis has junior synonyms such as S.mercerii, S.floridanus, and S.californicus.[4] American paleontologist Annalisa Berta considered the holotype of S.fatalis too incomplete to be an adequate type specimen, and the species has at times been proposed to be a junior synonym of S.populator.[3] Swedish paleontologists Björn Kurtén and Lars Werdelin supported the distinctness of the two species in 1990.[8]
question: When was the Smilodon discovered?
answers: 19th century onwards