Rediscovering Lutra lutra from Grotta Romanelli (southern Italy) in the framework of the puzzling evolutionary history of Eurasian otter

A river otter hemimandible has been rediscovered during the revision of the historical collections of G.A. Blanc from Grotta Romanelli, complementing the ongoing multidisciplinary research fieldwork on the site. The specimen, recovered from the level G ("terre rosse"; early Late Pleistocene or late Middle Pleistocene), is here assigned to Lutra lutra. Indeed, morphological and morphometric comparisons with other Quaternary Lutrinae fossils from Europe allow to exclude an attribution to the relatively widespread and older Lutra simplicidens, characterized by distinctive carnassial proportions. Differences with Cyrnaonyx antiqua, which possessed a more robust, shellfish-feeding dentition, support the view of a successful niche repartition between the two species during the late Middle to Late Pleistocene of Europe. The occurrence of Lutra lutra from the "terre rosse" of Grotta Romanelli suggests deep modifications of the landscapes due to the ecological adaptation of the taxon, and indicates that the Eurasian otter spread into Europe at the Middle-Late Pleistocene transition.