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Reanalysis of Sahelanthropus Fossils Points to Early Bipedal Adaptations

Researchers used 3D morphometrics to argue the 6.7–7.2 million-year-old primate shows hip traits linked to upright walking.

Overview

  • Published in Science Advances, the study led by Scott A. Williams identifies a prominent femoral tubercle interpreted as the attachment site for the iliofemoral ligament associated with bipedal stability.
  • The team also reports femoral antetorsion, a gluteal muscle attachment feature, and a relatively long femur compared with the ulna, aligning more with hominins than with modern apes.
  • Authors conclude Sahelanthropus likely mixed ground-based bipedalism with tree-based behaviors, indicating a gradual, mosaic evolution of locomotion.
  • The analysis re-examines limb fossils previously assessed in a 2022 Nature study and involves researchers from NYU, the University of Washington, Chaffey College, and the University of Chicago.
  • Skepticism persists among some specialists, and whether Sahelanthropus was a direct ancestor or a close relative on a side branch remains unresolved.