EURHINODELPHINIDS FROM THE EARLY MIOCENE OF PERU: FIRST UNAMBIGUOUS RECORDS OF THESE HYPER-LONGIROSTRINE DOLPHINS OUTSIDE THE NORTH ATLANTIC REALM

• Main Authors: Lambert, Olivier, De Muizon, Christian, Varas-Malca, Rafael, Urbina, Mario, Bianucci, Giovanni
• Other Authors: Chimie et Biologie des Membranes et des Nanoobjets (CBMN), École Nationale d'Ingénieurs des Travaux Agricoles - Bordeaux (ENITAB)-Institut de Chimie du CNRS (INC)-Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Museo de Historia Natural de Lima (MHN), Universidad Nacional Mayor de San Marcos (UNMSM), Dipartimento di Scienze della Terra Pisa, University of Pisa - Università di Pisa
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Cetacea; Odontoceti; Eurhinodelphinidae; Chilcatay Formation; Burdigalian; southeastern Pacific; [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology; Pacific; Pisco; North Atlantic
• Online Access: https://hal.sorbonne-universite.fr/hal-03256619; https://hal.sorbonne-universite.fr/hal-03256619/document; https://hal.sorbonne-universite.fr/hal-03256619/file/15124-Article%20Text-44928-1-10-20210126%281%29.pdf

International audience Among the many hyper-longirostrine dolphins (Odontoceti) from the Miocene, members of the family Eurhinodelphinidae bear two highly distinctive cranial features: a long and edentulous premaxillary portion of the rostrum and a mandible that is significantly shorter than the rostrum. Until now, unambiguously attributed members of this clade were only recorded from early to middle Miocene deposits of the North Atlantic realm (east coast U.S.A., North Sea Basin, and Mediterranean). In this work we describe and compare two partial skulls of longi-rostrine dolphins from late early Miocene (Burdigalian, 19.25-18 Ma) marine deposits of the Chilcatay Formation, in the East Pisco Basin (southern coast of Peru), preserving rostral and mandibular material, as well as ear bones. Based on these specimens we report diagnostic remains attributable to this family for the first time for the whole Southern Hemisphere and the whole Pacific Ocean. This major expansion of eurhinodelphinids’ palaeogeographic distribution contrasts with their proposed shallow-water, coastal environments; it suggests a new dispersal route for members of the family across the Central American Seaway; and it further highlights the similarities between the odontocete faunas of the southeastern Pacific and North Atlantic realm during the Miocene. Better-preserved eurhinodelphinid speci-mens from the odontocete-rich Chilcatay Formation will allow for a more detailed comparison with North Atlantic members of the family