TAPHONOMIC HISTORY OF CRUSTACEAN CUTICLE: CAUSES OF VARIABLE PRESERVATION

Crustaceans are important members of both fossil and modern ecosystems, and their presence in fossil assemblages can provide a wealth of information about paleoenvironments and post-burial diagenetic conditions. Studies of cuticle taphonomy have shown that preservation can be quite variable within the same formation, or even within the same individual fossil. Notable differences include the color of cuticle and the quality of preservation. Brachyuran crustacean specimens collected from the Lincoln Creek Formation (Washington, USA), Estancia 25 de Mayo Formation (Santa Cruz, Argentina), and others show variations in cuticle ranging from black, brown, and white in color, and poor to excellent quality. Within individual fossils, differences in color are also observed, particularly between different regions of the carapace, and claws. This study will seek to explain these differences using analytical chemistry techniques, including energy dispersive spectroscopy, and Raman spectroscopy. These methods combined will be able to detect organic molecules, mineral phases, and elemental differences in cuticles which could account for the observed variations in appearance. This will allow us to draw broader conclusions about the environmental and taphonomic factors which lead to variations in preservation, and enable us to use crustacean cuticles as proxies for certain conditions. The result will be an increase in the utility of crustaceans as indicators of both chemical and physical environmental and taphonomic conditions.