Marine benthic communities in the Upper Devonian of New York



Four distinctive benthic communities occur in the mid-shelf deltaic deposits of the Upper Devonian Sonyea Group: the Bellerophon Community, dominated by herbivorous gastropods and deposit-feeding bivalves; the Prodrtctella Community, dominated by brachiopods with adaptations for life on muddy substrata; the Cypricardella Community, dominated by bivalves and brachiopods with a variety of adaptations; and the Rhipidomella Community, dominated by brachiopods adapted for life on sandy substrata. The geographic and stratigraphic occurrence of the communities suggest that their distribution was controlled by two principal sets of environmental variables: (1) onshore to offshore gradients in salinity, dissolved oxygen concentrations, and sedimentary substrata, and (2) rate of delta progradation. A change in the rate of delta build-out during mid-Sonyea time led to a dramatic change in onshore to offshore community patterns. The change suggests that great care must be used in constructing generalized community models for longer intervals of Paleozoic time.