Taphonomy of Brachiopods from Devonian Carbonate Records

Understanding the effect of physical and biological processes on fossil preservation is critical for evaluating the quality of paleobiological information that can be extracted from fossil records. Deposit-level properties, which are used to describe shell bed characteristics as a whole, are often indicative of the final depositional processes. Taphonomic signatures, which characterize alteration on individual brachiopod shells within a shell bed, are representative of the environment before burial. This study investigates shell alteration patterns across Devonian carbonate environments, depositional basins, and deposits with different shell packing densities. Individual brachiopod shells were scored in this section according to the presence and degree of disarticulation, fragmentation, bioerosion, micritization, and encrustation. The taphonomic data demonstrated significantly higher levels of micritization in shallow subtidal facies than other depositional environments. Significantly higher micritization levels were also observed within intermediate and deep subtidal facies from Iowa. Taphofacies types, based on taphonomic signatures, do not correlate to deposit types, based on deposit-level properties. This supports the idea that there are different processes acting at different scales, especially in carbonate settings. This quantitative analysis provides insights into the biological and physical processes that influence preservation of the fossil record.