UTILIZING MICROCT AND FEA TO EXAMINE PARASITE-INDUCED SKELETAL PATHOLOGIES IN FOSSIL AND MODERN DECAPOD CRUSTACEANS

The fossil record of parasitism appears to be remarkably poor, and despite the recognition that this biotic interaction drives evolutionary and ecological adaptations and shapes ecosystem structure, remains understudied. The fossil record of crustaceans is also limited, and often fragmentary, owing to a lightly to moderately calcified exoskeleton that readily disarticulates in the absence of soft tissue. For these reasons, despite a remarkable diversity and distribution of crustacean parasite-host ecologies, and increasing scientific interest in the fossil record of biotic interactions, the ecological and evolutionary history of crustacean parasites is poorly constrained. Among the best evidence of crustacean parasites on decapods in the fossil record is the ichnotaxon Kanthyloma crusta, a conspicuous branchial swelling on decapod carapaces typically associated with infestation by parasitic Epicaridean isopods, which has been described on fossil carapaces of decapods, primarily Brachyura and Galatheodea, since the Jurassic. The rapidly increasing accessibility of advanced tools and instruments for creating and analyzing 3D fossil data allows us, for the first time, to analyze the mechanical taphonomic impact and internal morphology of these unique skeletal pathologies in fossil and modern specimens. Here, we use X-ray micro computed tomography (microCT) and photogrammetry to create and compare high-fidelity digital anatomical models of modern and fossil decapod carapaces with branchial swellings attributable to ichnotaxon K. crusta. Finite elements analysis (FEA) is used to assess the mechanical impact of K. crusta on function and taphonomy.