Orrorin tugenensis is considered to be the second-oldest known hominin ancestor that is possibly related to modern humans and is the only species classified in genus Orrorin. The name was given by the discoverers who found Orrorin fossils in the Tugen Hills of Kenya. By using radiometric dating techniques, the volcanic tuffs and lavas, faunal correlation and magneto-stratigraphy, the strata in which the fossils were found were estimated to date between 6.1 and 5.8 million years ago, during the Miocene. This find is important because it is possibly an early bipedal hominin.