Early Ordovician bryozoans from north-western Russia

ABSTRACT. A bryozoan assemblage from the Billingen Stage of north-western Russia (Ingria) is apparently the oldest known in the world. It consists of six species distributed among the trepostomate genera Esthoniopora Dianulites, Revalotrypa Phragmophora and Hemiphragma . Two species are new: Phragmophora lavaense Pushkin, sp. nov. and Hemiphragma priscum Pushkin, sp. nov. The bryozoans are characteristic of the medium diversity benthic fauna of uncertain origin which migrated into the Baltic Basin during Billingen time (late Prioniodus elegans — early Oepikodus evae zones). The Billingen bryozoans have a close similarity to the late Arenig bryozoan faunas of Baltoscandia that are also dominated by trepostomates, but differ significantly from the low diversity late Arenig bryozoan assemblages of North America, Ireland, North China, Vajgach and Novaja Zemlja.