Exploring the preservation of a parasitic trace in decapod crustaceans using finite elements analysis

The fossil record of parasitism is poorly understood, due largely to the
scarcity of strong fossil evidence of parasites. Understanding the
dynamics of preservation for fossil parasitic evidence is critical to
contextualizing the fossil record of parasitism. Here, we present the
first use of X-ray computed tomography (CT) scanning and finite elements
analysis (FEA) to analyze the impact of a parasite-induced fossil trace on
host preservation. Seven fossil and modern decapod crustacean specimens
with branchial swellings attributed to an epicaridean isopod parasite were
CT scanned and examined with FEA to assess differences in the magnitude
and distribution of stress between normal and swollen branchial chambers.
The results of the FEA show highly localized stress peaks in reaction to
point forces, with higher peak stress on the swollen branchial chamber for
all specimens, suggesting a possible shape-related decrease in the
preservation potential of these parasitic swellings. Broader application
of these methods as well as advances in the application of 3D data
analysis in paleontology are critical to understanding the fossil record
of parasitism and other poorly represented fossil groups.