Orrorin tugenensis was discovered in 2001 in the Tugen Hills of Kenya. Slightly younger than Sahelanthropus, Orrorin suffers from the opposite challenge: there have been no cranial specimens recovered thus far. The discoverers speculate Orrorin was indeed bipedal, based largely on evidence gleaned from the recovered femora. The cortical thickness of the postcranial remains suggests bipedalism, though not necessarily obligatory bipedalism. The arms suggest an arboreal lifestyle was still a significant part of Orrorin’s existence — a suggestion reinforced by other aspects of the fossil remains, such as the size, shape, and wear patterns of the teeth. All of these features lend support to the woodland paleoenvironment predicted for Orrorin.