Craniodental morphology of Propotamochoerus palaeochoerus (Suidae: Suinae) from the late Miocene of els Hostalets de Pierola (Vallès-Penedès Basin, NE Iberian Peninsula): systematic and biochronological implications

Abstract Suines originated in Asia during the Middle Miocene and dispersed into Europe by the early Late Miocene. Their first European record, which corresponds to Propotamochoerus palaeochoerus , was formerly dated to MN7+8 but recent data have suggested an earliest MN9 age. Although P. palaeochoerus has long been known from the fossiliferous area of els Hostalets de Pierola, dating inaccuracies have precluded ascertaining its earliest appearance. In contrast, the remains from the stratigraphic sequence of Abocador de Can Mata (ACM), in the same area, are precisely dated through litho-, bio-, and magnetostratigraphic correlation, allowing us to determine its first record there. Here we describe previously unpublished remains from the Hostalets area, including 75 isolated teeth, 27 dentognathic fragments, and two crania. Qualitative and metrical comparisons support an attribution to P. palaeochoerus , while a cladistic analysis suggests close relationships between Propotamochoerus and Hippopotamodon , supporting their classification into the tribe Dicoryphochoerini. The oldest ACM record of P. palaeochoerus has an interpolated age of 11.23 Ma (subchron C5r.2r), representing the earliest securely dated record of the species in the Vallès-Penedès Basin. This predates by ~50 kyr the first appearance datum of hipparionin horses in this basin at 11.18 Ma (subchron C5r.1n). Coupled with recently published evidence from Central Europe, it is suggested that P. palaeochoerus may have dispersed into Europe slightly earlier than hipparionins. However, dating uncertainties about the first appearance datum of hipparionin horses in Europe do not currently allow to discount a roughly synchronous dispersal with P. palaeochoerus , giraffids, and other eastern immigrants ~11.3–11.2 Ma.