How does the position of the foramen magnum in Ardipithecus support evidence for upright walking?

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skeleton of “Ardi” — Ardipithecus Reconstructed frontal view of the skeleton of “Ardi,” a specimen belonging to the early hominid species *Ardipithecus ramidus*.

In the genus Ardipithecus, specifically the species Ar. ramidus, the position of the foramen magnum serves as a key indicator of bipedal locomotion.1

In quadrupedal apes, the foramen magnum is located posteriorly at the base of the skull, which is consistent with a posture where the head hangs from the end of the vertebral column. In contrast, the foramen magnum of Ar. ramidus is positioned under the braincase. This forward placement is a characteristic feature of bipeds, as it allows the head to be balanced more vertically atop the vertebral column, facilitating upright walking.12