Clavate borings in a Miocene cetacean skeleton from Tarragona (NE Spain) and the fossil record of marine bone bioerosion

Clavate borings found in the tympanic bulla of a Miocene cetacean from El Camp de Tarragona Basin constitute the first evidence of the ichnogenus Gastrochaenolites in bones of an autochthonous cetacean carcass. Previous records of similar trace fossils on marine bones were described from transported or reworked remains. Based on their morphology and ichnotaxonomy, the borings are assigned to the activity of pholadid bivalves, which would have colonized the skeletal carcass on the sea floor after removal of covering soft tissues. Sedimentological and paleontological data indicate a low-energy depositional setting with low sedimentation rate, which would have provided the temporal window for bivalve colonization. This new finding contributes to widen our knowledge of bioerosion in marine vertebrate skeletons.