Organisms Attached to Conulariid Thecae from the Upper Ordovician of the Barrandian Area (Czech Republic)

In the middle Sandbian and lower Katian (Upper Ordovician) rocks of the Barrandian area, the fossil remains of conulariids are relatively abundant. Their thecae were sometimes used as solid surfaces for the attachment of epizoans, mostly craniid brachiopods of the genus Petrocrania, more rarely also echinoderms Hemicystites and Agelacrinites, and bryozoans Ceramopora and Spatiopora. The orientation of shells of Petrocrania suggests that conulariids (mostly belonging to the genus Archaeconularia) were dead at the time of the brachiopod attachment, their thecae were partly fragmentary and secondarily replaced. A find of Pseudoconularia grandissima attached to the theca of the cystoid Codiacystis is also reported.