ASSESSING IMPACTS OF PARASITE PATHOLOGIES ON PRESERVATION OF FOSSIL DECAPODS USING FINITE ELEMENTS ANALYSIS

The fossil record of parasitism is often characterized as generally poor, and typically treated as unsuitable for quantitatively rigorous analysis of evolutionary and ecological trends across broad spatial or temporal scales. As a result, the ecological and evolutionary impact of parasitic biotic interactions in deep time remain a relatively underdeveloped subject of study in comparison to the large body of work exploring the importance of predation in the fossil record. Neontological studies demonstrate the tremendous diversity and abundance of extant parasites and their integral part in shaping modern ecosystems, highlighting the need to better understand the taphonomic processes hindering quantitative exploration of parasite paleobiological data. Here, we present a case study exploring the preservation of trace-producing parasitic interactions targeting crustaceans. Extant crustaceans exhibit incredible diversity as parasites and hosts of parasites, of which only a relatively small number of crustacean parasite-host interactions have been identified in the fossil record. Of these identified interactions, the parasite-associated swelling trace Kanthyloma crusta, attributed to infestation of decapods by epicaridean isopods, is among the best characterized, and has been identified on over 100 fossil decapod species spanning at least the late Jurassic to the recent. We characterize the taphonomic impact of these swellings on host decapods using Finite Elements Analysis (FEA). FEA was used to assess differences in the peaks and distribution of stresses between healthy and swelled branchial chambers, using seven models of fossil and modern parasitized decapods across three species created using CT-scanning. We find measurable differences in peak stress in parasitized branchial chambers, indicating that the presence of this pathology compromises the structure, which in turn likely hinders preservation during fossilization. This highlights the need for quantitative approaches to disentangle fossil record biases and further explore the fossil record of parasitism in the context of phylogenetic, morphological, and ecological patterns.