Introduction

Sedimentary petrologists define diagenesis as the “alteration of sediments after deposition” (Retallack 1990:129). It is, however, sometimes taken to mean only “alteration after burial” (Retallack 1990:129). Throughout this volume I take diagenesis to have the latter meaning for vertebrate faunal remains. The importance of this distinction resides in the many post-depositional and preburial taphonomic processes that can modify vertebrate remains, along with modifications resulting from the burial process itself.

Once animal remains have been buried, a number of taphonomic processes can act on them. Some of the more familiar ones are mineralization and deformation. In this chapter, these and other diagenetic processes are discussed. Diagenesis of skeletal tissues is affected by intrinsic factors of the tissue specimen, such as its size, porosity, chemical and molecular structure, and by extrinsic factors such as sediment pH, water and temperature regimes, and bacterial action (Von Endt and Ortner 1984). Intrinsic factors such as hydrolysis of collagen by bone water may exacerbate or buffer extrinsic factors. The post-burial history of animal remains involves their preservation as fossils (e.g., Schopf 1975), and their chemical and mechanical alteration or destruction.