Lower Palaeozoic plankton

Abstract

The graptolite biocoenosis is accepted as the epipelagic or oceanic plankton fauna of the Lower Palaeozoic, although the geosynclinal deposits in which graptolite remains occur are not typically oceanic. Local variation within geosynclines implies a measure of permanence and stability in their faunas, but the general similarity in graptolite successions calls for frequent intercommunication, and epipelagic plankton probably drifted into geosynclinal seas from outlying oceanic areas. The location of these oceans introduces the problem of continental drift.