A cetotheriid whale from the upper miocene of the mediterranean

Cetotheriids are a once diverse clade of baleen whales with a rich Miocene–Pleistocene fossil record. In the Northern Hemisphere, they are abundant along the coasts of the Atlantic, Pacific and the Paratethys but – surprisingly – not the Mediterranean. Here, we describe a partial mandible from the upper Miocene Arenaria di Ponsano Formation exposed near Pisa (Tuscany, Italy), which unequivocally represents a cetotheriid based on its low, broadly triangular coronoid process, obliquely oriented condyle, deeply excavated subcondylar furrow, and posteriorly elongated angular process. Our new specimen highlights the apparent rarity of this family in the Mediterranean, which may re-flect local competition with ecologically similar grey whales (a pattern that, if true, seemingly does not apply to adjacent North Atlantic). The latter, in turn, may explain the geographical isolation and disparate anatomy of the seemingly endemic Paratethyan cetotheriines.