Ribs are naturally fragile and, as a consequence, are rarely preserved in the fossil record. The costal elements recovered from the KSD-VP-1/1 partial skeleton are important evidence allowing reconstruction of the hominin thoracic cage. The ribs of KSD-VP-1/1 are examined with respect to their implications for the evolution of Australopithecus afarensis thoracic morphology. Angulation and torsion along the rib corpus and rib declination indicate a broad upper thorax and a deeply invaginated thoracic vertebral column. Implications for the early hominin thoracic bauplan are discussed.