The taxonomy and palaeoecology of Bryozoa from the upper Permian zechstein reef of N.E. Eng1and

Abstract

Eighteen species of Bryozoa are described from the Upper Permian zechstein reef - they are assigned to ten genera in the Orders Fenestrata, Trepostomat and cyclostomata. Emended diagnoses are given at various levels and superspecific taxonomic categories within the Fenestrata are discussed. The examination of type specimens and of a large suite of new material has allowed the limits of intraspecific morphological variability to be defined and has resulted in the synonymising of several species. Three new taxa are described, for which holotypes have been designated :- Ryhopora delicata gen. nov., sp. nov. Acanthocladia magna sp. nov. and Penniretepora waltherinodata subsp. nov. The genera Penniretepora and Kalvariella Are recorded for the first time from the Zechstein reef in N.E. England. Aspects of bryozoan palaeobiology And functional morphology have been inferred at zooid and colony level. A type of ovicell, new in the Fenestrata, is described and is compared with those of the Cheilostomata; the taxonomic significance of this chAracter is assessecl. Patterns of zooid-generated feeding currents are inferred and some correlation of intraspecifically varying zoarial morphology with environment is suggested. The characteristic distribution of Bryozoa in relation to Zechstein reef sub-environments is described. An analysis of species abundance and diversity demonstrates a marked faunal impoverishment in reef-flat communities; new evidence for contemporaneous reef lithification is assessed.