Obturator externus groove explained

The obturator externus groove is the groove on the posterior neck of the femur for the insertion of the obturator externus muscle, a muscle that is important during bipedal locomotion. It is located within the depression of the trochanteric fossa.

This landmark is used as evidence of bipedal locomotion in the hominins.^[1] 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.^[2]

Notes and References

1. Stern . Jack T. . Larson . Susan G. . 1993-05-01 . Electromyographic study of the obturator muscles in non-human primates: implications for interpreting the obturator externus groove of the femur . Journal of Human Evolution . en . 24 . 5 . 403–427 . 10.1006/jhev.1993.1029 . 0047-2484.
2. Pickford . Martin . Senut . Brigitte . Gommery . Dominique . Treil . Jacques . 2002-09-01 . Bipedalism in Orrorin tugenensis revealed by its femora . Comptes Rendus Palevol . en . 1 . 4 . 191–203 . 10.1016/S1631-0683(02)00028-3 . 1631-0683.