The obturator externus groove is the groove on the posterior neck of the
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
for the insertion of the
obturator externus muscle, a muscle that is important during bipedal locomotion.
This landmark is used as evidence of
bipedal locomotion in the
hominin
The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas).
The t ...
s. The fossil ''
Orrorin tugenensis'' (6-7 mya) possesses the
obturator externus groove, which suggests that it moved bipedally and could represent one of the earliest fossils with evidence of bipedal locomotion.
Bones of the lower limb
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