Palaeobiogeography of Famennian (Late Devonian) bryozoans

Abstract

Bryozoans were widely distributed in marine habitats of the Famennian (Late Devonian) worldwide. This time interval was marked by gradual change in taxonomic composition of bryozoan faunas, which were insignificantly affected by global events (Upper Kellwasser, Handerberg). Distribution of bryozoan faunas was controlled by intrinsic factors (macroevolution) as well as extrinsic factors (eustasy, plate tectonic and volcanic activity). Palaeobiogeographic analysis of bryozoan associations reveals closest similarities between Tian Shan and Kazakhstan during the early to middle Famennian and between the Altay-Sayan Fold Belt, Transbaikalia and Mongolia during the late Famennian. Migration patterns of bryozoan faunas during the Famennian are reconstructed, showing main dispersions from the marine basins of Northern China to Kazakhstan and western offshoots of Tian Shan, and then to other areas. Biostratigraphic markers based on bryozoan taxa are established for each substage (lower, middle and upper Famennian) within relevant regions.