First Mediterranean record of the delphinidan genus Kentriodon from a new Lower Miocene odontocete locality at Feltre (northeastern Italy)

Fossil odontocetes from the “Belluno Molasse” (Friulian-Venetian basin, northeastern Italy) have been mainly studied and described by Giorgio Dal Piaz in the early 20th century. These historic finds originate from outcrops in the neighborhood of Belluno where the Lower Miocene Libano Sandstone was quarried. This odontocete assemblage depicts a costal-marine (or even estuarine) fauna that includes seemingly endemic lineages such as Dalpiazinidae and Eoplatanistidae. The odontocete remains from the Belluno area are crucial to understand the diversity and richness of marine vertebrate communities in the Early Miocene, a key moment for the evolutionary radiation of many odontocete lineages. New odontocete remains have recently been found by one of the authors (P.V.) in the Colle della Croce quarry (Feltre, Belluno Province). The strata cropping out therein belong to the aforementioned Libano Sandstone (represented by a distal, fine-grained facies) and to the overlying Bolago Marl, both dating back to the Early Miocene. Most of the odontocetes from the Colle della Croce quarry (including the specimen here examined) originate from the Bolago strata, which we have preliminarily dated to the Burdigalian by means of nannoplankton biostratigraphy. In the present work, we focus on a partial cranium including associated ear bones (right petrosal, stapes, malleus and right tympanic bulla). This specimen was recovered from the Bolago Marl strata of Colle della Croce quarry and is housed at “Museo Civico Archeologico” in Feltre. Osteoanatomical considerations and comparisons with other earlybranching delphinidans kentriodontid genera allow to assign the cranium and ear bones to the kentriodontid genus Kentriodon. This is the first record of Kentriodon in the Mediterranean Basin – one that fills a palaeobiogeographical gap in the distribution of this genus, which was widespread globally during the Early and Middle Miocene.