Second rib curvature in apes and humans and implications for the evolution of thoracic shape in early hominins [abstract]

Abstract

Thoracic form in humans is often described as "barrel-shaped" with a broad upper rib cage, a condition different from great apes, who have a "cone-shaped" thorax and narrower upper rib cage. The earliest Australopithecus has been described as "cone shaped," but fossil evidence for thoracic shape is limited. Still, this inference has been used to infer important aspects of early hominin biology, such as gut size and locomotor capacity. In June 2010, a new skeleton of Australopithecus afarensis (KSD-VP 1/1) from Korsi Dora, Ethiopia, was announced that it preserves a nearly complete second rib. Its curvature resembled those of humans more than African apes.