Biogeography of Silurian Stromatoporoids

Stromatoporoids were widespread in the Ordovician, Silurian and Devonian shallow seas with carbonate types of sedimentation. Their occurrences in reefs and association with bahamitic type carbonate sediments, sometimes replaced by evaporites, allow them to be considered as stenothermal warm-water organisms which lived in the tropical to subtropical climatic belt between 40° N and S. The rapid eustatic deepening after the latest Ordovician glaciation gave rise to ecological stress in the shallow-water stromatoporoids and suppressed their adaptive radiation. Therefore a taxonomically monotonous cosmopolitan fauna of stromatoporoids formed at the beginning of the Llandovery. Few endemic genera existed during the late Llandovery and Wenlock. In Ludlow time a low degree of provincialism appeared when differences developed between the European and Asiatic faunas; these vanished again in the Pridoli. The data on stromatoporoid distribution are in good agreement with the current palaeogeographical reconstructions