Diagenetic alterations of micromammal fossil bones from Olduvai Bed I of the lower Pleistocene sequence at Olduvai Gorge, Tanzania

Abstract

ABSTRACT Analyses of the organic and inorganic components of various small mammal fossil bones from nine stratigraphic levels of Bed I, Olduvai Gorge, Tanzania, spanning 100,000 years show some differences that relate to environmental factors but not to chronological sequence. All fossil bones are compositionally altered relative to modern counterparts, with the organic components both extensively lost and chemically modified, and all display large crystallinity changes. Each of the stratigraphic levels has distinctive subtle features, but with greatest differences recorded from the FLKZinj and FLKN5-6 levels. From observations of post-mortem features, including modified bone morphology and taphonomic alterations to bone surfaces, together with the compositional and structural differences, it is concluded that localized differences in burial diagenesis existed, and that predation was a contributory factor to the overall diagenetic process. These results illustrate the importance, and future potential, of a combined taphonomic and diagenetic approach to understanding the processes involved in bone diagenesis.