Permian bryozoans from the Nemda horizon (Roadian) of Samara Region, Russia

Abstract

© 2019, Paläontologische Gesellschaft. Six bryozoan species are described from the Lower Roadian (Guadalupian) of the eastern part of the East European Platform. The studied fauna is abundant and represented by various growth habits (branching, massive, encrusting, reticulate), developed in local bioherms. The studied bryozoan assemblage consists of trepostomes (three species), fenestrates (two species) and one cryptostome species with specific exozonal skeletons. Trepostomes of genus Dyscritella are dominant in this bryozoan association and possess acanthostyles differentiated by size. These structures probably performed protective and fixing functions. Fenestrate bryozoans have funnel-shaped and reticulate colonies with superstructure, which could have developed to protect against rapid sedimentation and predators. The identified bryozoan species are widely distributed within the East European Platform, with some similarities to the Roadian fauna of Transcaucasia, Guadalupian fauna of the Primorskij Kraj and Omolon massif.