Bryozoa of the Mojcza Limestone

Fragments of bryozoan colonies with phosphatic coats occur abundantly throughout the section of the Mojcza Limestone. They provide a record of faunal evolution in the area from the end of the Arenig to the beginning of the Ashgill. Single-walled palaeotubuliporine Cyclostomata and ramose gracile rhabdomesines dominate the assemblages, and typical Trepostomata and Cryptostomata, prevailing in coeval faunas in other regions, are virtually absent in Mojcza . The Mojcza fossil assemblages are also unusual in the abundance of early astogenetic stages of bryozoan colonies, probably due to high juvenile mortality on the soft bottom with few detrital particles suitable for settlement of larvae exposed. This enables recognition of single-walled stages in colony development of several species of the rhabdomesines and related bryozoan