Parasites of Ammonoids

Abstract

Extant cephalopods are commonly infested by parasites making it plausible that ammonoids also had parasites. We review the fossil evidence of parasitic infestations in ammonoids, which, due to low preservation potential of soft-tissues in ammonoids and parasites, are mainly recorded as shell pathologies on the external shell interpreted to be caused by parasites. Extant nautilids are of little help to interpret these structures as they only harbor parasitic copepods. Pathologies analogous to those found in ammonoids that are caused by parasites are common in extant bivalves and gastropods. The position of these features might reveal their parasitic nature. The restriction of these structures to certain ammonoid lineages suggests both the influence of phylogeny and the potential role of ecology (feeding, mode of life) on infestation risks. Other long-term associations with detriment to ammonoids such as epizoa and bioeroders as well as their possible confusion with parasitism are briefly discussed.