In the original description in 2002, Brunet "et al." said it "would not be unreasonable" to speculate that "Sahelanthropus" was capable of maintaining an upright posture while walking bipedally. Because they had not reported any limb bones or other post-cranial material (anything other than the skull), this was based on the reconstructed original orientation of the foramen magnum (where the skull connects the spine), and their classification of "Sahelanthropus" into Hominina based on facial comparisons (one of the diagnostic characteristics of Hominina is bipedalism). This was soon disputed because the orientation of the foramen magnum is not an entirely conclusive piece of evidence in regard to the question of habitual posture, and the features used to classify "Sahelanthropus" into Hominina are not entirely unique to Hominina. In 2020, the femur had been formally described, and the study concluded it was not consistent with habitual bipedalism.