Authors: Jaroslav Marek, Radko Šarič & Petr Kácha
Full version (29,336 kB)Abstract: As yet undescribed accumulations of shells of orthoconic cephalopods, which are in someAs yet undescribed accumulations of shells of orthoconic cephalopods, which are in someaspects comparable to cephalopod limestones known from the Silurian and Lower Devonian of theBarrandian area and other regions of the world, occur in the Letná and Zahořany formations (middleSandbian and lower Katian stages, Upper Ordovician, central Bohemia). These accumulated shells areoften colonized by sessile organisms. Only a small proportion of these organisms could be attachedto shells of alive cephalopods; the majority of them used empty shells as solid substrates. The mostabundant epizoan is the cystosporate bryozoan of the genus Ceramopora that often overgrows the cephalopodshells extensively. Holdfasts of the genus Sphenothallus and problematic fossils assigned to the genus Conchicolites are common. Rarer epibionts include the bryozoan Spatiopora, the cystoid echinoderm Codiacystis and the brachiopod Ptychopeltis. Varying sizes of bryozoan colonies occurring on the samecephalopod shell point to several recurring attachment events, probably reflecting reproduction cycles.
