Studies on the condition and structure of bone of the Saldanha fossil cranium

Abstract

The external surface of the Saldanha cranium shows extensive exfoliation and cracking. In a few places remnants of the probable original bone surfaces can be observed. These are orange-brown in color, contrasting with the nearly white color of exposed deeper layers, and are subdivided into small segments with pits in their centers. Causes of the color differences are uncertain but merit investigation. The surface cracking and exfoliation probably result from weathering before fossilization. This conclusion is based on the observation that the endocranial surfaces show no such effects, despite the scattering of the cranial fragments at the time of discovery. A depressed fracture in the frontal bone indicates a heavy blow at or shortly after the time of death. This blow probably created some of the fragments, but there are also incomplete fracture cracks which may have resulted from the blow. Unresolved taphonomic problems include the manner in which the cranium held together after decay of soft tissues allowed weathering, and the manner in which the fragments were subsequently scattered. Chips from the cranial vault indicate that the outer table was very thick, tending to support recent proposals that the specimen and assoicated fauna and tools are from a considerably earlier time period than originally believed. The surface damage to the brow ridges gives information on the structure of deeper layers. These are lacking orientation, supporting the hypothesis that hominid brow ridges are not primarily a response to masticatory forces, but may afford protection for the eyes.