Solubility profiles of synthetic apatites and of modern and fossil bones

Abstract Strontium has been shown to vary within trophic levels in natural foodwebs so that previous criteria used to identify biogenic strontium in fossils, namely consistent differences between herbivores and carnivores, may be inappropriate. In this article, two alternative approaches are explored. These include first, experimental studies of the behaviour of synthetic apatites in the solubility profile system, and second, solubility profile studies of fossils from the Pleistocene site of Swartkrans. The synthetic apatite studies show that simple mixtures of apatites dissolve discretely in the system. Study of Swartkrans specimens reveals that, while diagenetic Sr is clearly present, some recoverable Sr varies in a manner similar to that seen in modern African foodwebs, and is therefore unlikely to be of diagenetic origin.