Taxonomy and paleoecology of the giagantoproductids of Nova Scotia

The gigantoproductids (Brachiopoda) of the Upper Windsor (Mississippian) in Nova Scotia are represented by the genera Gigantoproductus Prentice and Semiplanus Sarycheva. The two genera can be separated on the basis of external morphologic variations that can be defined statistically in the mature stages, and on the basis of shell thickness in the mature forms. Immature specimens of Gigantoproductus are rare and cannot be distinguished from Semiplanus on the basis of external features alone. The two occur in a faunal association with Lithostrotion which lived in a shallow water, marine environment, below wave base. The record of this environment is the Musquodoboit Biofacies. The smaller genus, Semiplanus, also lived in deeper water represented by the Herbert River Biofacies. Gigantoproductus is restricted to the Gigantoproductus Unit of the Musquodoboit Limestone. The local forms resemble species present in Visean age marine limestones of Western Europe and belong to the species Gigantoproductus giganteus (Sowerby) and Semiplanus latissimus (Sowerby). The local species are found together in the C Subzone which correlates with the Dibunophyllum Zone of the Late Visean of Western Europe.