Graptolite Faunal Provinces in Ordovician of Northwest Europe

Early Ordovician grap to lites in Europe and North America give some suggestion of Atlantic and Pacific Provinces, but the differences are not great and the faunas intergrade. The influence of environment may be quite significant. Thus, some forms may have adapted better to surface waters than others. There was also some provincial differentiation in the Upper Ordovician , but at the specific rather than the generic level. The stand ard British zonal sequence is a composite of forms from the Atlantic and Pacific Provinces, both of which are present in Britain.