On the stratigraphic position of the Delden Member (Breda Formation, Overijssel, the Netherlands) with implications for the taxonomy of Pygocardia (Mollusca, Bivalvia)

Re-identification of parts of the mollusc fauna of the Delden Member, especially Pygocardia and Panopea species, from the vicinity of Delden (Overijssel prov., the Netherlands) and comparison with other Neogene faunas from the southern North Sea Basin imply a late Early to early Late Pliocene age for the Delden fauna, that usually is attributed to the Miocene. Shell measurements performed for this study revealed that the species definitions for Pliocene North Sea Basin Pygocardia are inadequate.