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    Biotic interactions in the fossil record: an investigation on the patterns of predation and parasitism of Plio-Pleistocene bivalves from the Nashua Formation of Florida

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    [EMBARGOED UNTIL 8/1/2023] The present study investigated for patterns of predation and parasitism among a collection of Plio-Pleistocene bivalves from the Nashua Formation of Florida. The processed sample yielded 2010 unique whole and broken valves representing 34 genera among 21 families. Traces indicative of predatory drill holes were the dominant trace type (7.7 percent; n=154) followed by trematode-induced pits and igloo-like structures (2.2 percent; n=45) and polydorid-induced traces (1.7 percent; n=35). Drillers strongly preferred Parvilucina and Cavilinga, polydorids preferred Mulinia and related forms and trematodes preferred Gemma and Mulinia and related forms as their preferred prey/host. Valve selectivity was found only for predatory traces in Caryocorbula and combined corbulids whereas site selectivities were recorded only in Mulinia and related forms where drilling predators selectively drilled the dorsal sectors and polydorid parasites preferentially parasitized the posterior sectors. Drilling predators were also size selective of their prey. We further explored if there is a trade-off between selecting parasitized versus healthy prey/hosts by testing for association, avoidance, or neutrality among the trace makers. No evidence for association or avoidance was found with the absence of patterns is best explained by the overall selection of taxa by the Nashua trace makers that limit competition and overlap between Nashua trace makers.Includes bibliographical references