New records of Hemisyntrachelus (Odontoceti, Delphinidae) from the late Pliocene or early Pleistocene of the southern North Sea

Rostral fossils of large dolphins are identified as belonging to the genus Hemisyntrachelus Brandt, 1873. They reconfirm and corroborate the presence of this genus in the late Pliocene or early Pleistocene of the North Sea. Comparison of these fossils with the holotypes of the known species of Hemisyntrachelus (H. cortesii (Fisher, 1829), H. pisanus Bianucci, 1996 and H. oligodon (Pilleri & Siber, 1989)) indicates that the North Sea specimens represent a different species which shows a peculiar morphology of the presphenoid. The incompleteness of the key fossils urges the authors to classify these finds temporarily as Hemisyntrachelus sp. Until more, and more complete specimens are identified or discovered.