Obturator externus groove

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.{{Cite journal |last=Stern |first=Jack T. |last2=Larson |first2=Susan G. |date=1993-05-01 |title=Electromyographic study of the obturator muscles in non-human primates: implications for interpreting the obturator externus groove of the femur |url=https://www.sciencedirect.com/science/article/pii/S0047248483710298 |journal=Journal of Human Evolution |language=en |volume=24 |issue=5 |pages=403–427 |doi=10.1006/jhev.1993.1029 |issn=0047-2484|url-access=subscription }} 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.{{Cite journal |last=Pickford |first=Martin |last2=Senut |first2=Brigitte |last3=Gommery |first3=Dominique |last4=Treil |first4=Jacques |date=2002-09-01 |title=Bipedalism in Orrorin tugenensis revealed by its femora |url=https://www.sciencedirect.com/science/article/pii/S1631068302000283 |journal=Comptes Rendus Palevol |language=en |volume=1 |issue=4 |pages=191–203 |doi=10.1016/S1631-0683(02)00028-3 |issn=1631-0683|url-access=subscription }}