BUG IN A JAR II: SHRIMP IN A JAR: THE MALACOSTRACENING

Soft-bodied fossil deposits, particularly those that rise to the quality of konservat lagerstätten, are valuable sources of paleontological and paleoecological information that can be found nowhere else. Understandably, much effort has been made to describe the taphonomy of these deposits, so that the fossils they hold and the environmental stories they can tell may be interpreted correctly. In recent years, actualistic taphonomic experiments have become a popular way to try to reproduce certain preservational pathways and modes; to reverse engineer, as it were, the conditions that can lead to soft-body preservation.

A previous iteration of this experiment series explored general questions of sediment interactivity and permeability barrier effects on the decay of sample soapberry bugs. The current experiment attempts to replicate conditions that have been hypothesized to lead to the Burgess Shale-type (BST) preservation mode, an important taphonomic window which showcases the evolution of animals during and shortly after the Cambrian Explosion in open marine settings. Specifically, does adding additional calcium to artificial seawater, to a level at or beyond that proposed to be typical of the Cambrian seas when the BST was prevalent, lead to the establishment of calcite seals in the upper levels of the sediment? And if so, do these seals reduce the extent of decay in buried peppermint shrimp, Lysmata wurdemanni?

Additionally, although taphonomists agree that the diversity and expressed metabolisms of decaying microbes are a critical component of soft-bodied preservation, few actualistic studies assay the microbes present during decay. Thus, we also include microbial assays of periodically extracted water and sediment samples to track the evolution of the microbial community over the course of the experiment treatments. This study serves not only to test the feasibility of a popular hypothesis of the critical BST of preservation, it also provides a methodological template for the actualistic study of other BST hypotheses. It could likewise be applied, with some modification, to other settings of soft-bodied fossil preservation, such as those typical of Mazon Creek, or Solnhofen/Waukesha-style carbonate platforms.