The tube ultrastructure of serpulids (Annelida, Polychaeta) Pentaditrupa subtorquata, Cretaceous, and Nogrobs cf. vertebralis, Jurassic, from Germany

Abstract

Calcitic prismatic structures occurred already in Jurassic serpulid tubes, here described in Nogrobs cf. vertebralis. In Cretaceous Pentaditrupa subtorquata (Serpulidae) the external layer of the tube has a semiregular spherulitic prismatic structure closely resembling that in the vitreous tube of recent Placostegus tridentatus but differing from the external hyaline layer of recent Ditrupa arietina (Serpulidae). The internal tube layer of P. subtorquata is presumably diagenetically altered and has a granular homogeneous structure. The prismatic structures seem to have the best preservation potential in fossil serpulid polychaetes.