Parasitism in Jurassic belemnites: examples from the upper Callovian of southern Poland

Deformation in samples of Hibolithes hastatus Montfort and ? Rhopaloteuthis Lissajous are documented from the upper Callovian Lamberti Zone of the Ogrodzieniec quarry, southern Poland. A specimen with hook-shaped bending is assigned to forma hamata Keupp, whereas other specimens with local thickening of the rostrum are assigned to another paleopathology, forma bullata Keupp. The absence of any external injury corroborated by high-resolution computed tomography suggests parasitism as the most probably cause for shell deformation. Identification of a specific parasite taxon is, however, hampered by the fact that parasites are typically small-bodied (submillimeter) and generally lack biomineralized hard parts. It must also be noted that different parasites can leave similar traces and taxonomically distant parasites can inflict similar symptoms on their hosts due to convergence in the evolution of host-exploitation strategies. In this regard, microtomography offers an innovative and non-destructive way to analyze the internal structure of a belemnite rostra. Hence, this contribution adds to the increasing body of evidence that the scan-based analyses provide a clearer picture of the internal structure of the paleopathology and that the classification of paleopathologies based only on external features (sensu Keupp) might lead to false inferences of their formational mechanisms.