Silurian biostratigraphy: revision of the North Atlantic Realm in the Llandovery

Abstract

Llandovery faunas have been considered more cosmopolitan than any others during the Lower Ordovician - Middle Devonian with only two undivided biogeographic Realms, the North Atlantic and Malvinokaffric, being recognised. Endemie pentameroids known from the Ashgill - Middle Llandovery of the Uralian region, Siberian Platform and adjacent Sette Daban occur commonly in North Greenland. Thus, during this time and in biofacies rich in pentameroids, the North Atlantic Realm appears divisible into a North Atlantic Region and a Uralian-Cordilleran Region, as in the Upper Silurian.