Isolated theropod teeth associated with sauropod remains from El Oterillo II (Early Cretaceous) site of Salas de los Infantes (Burgos, Spain)

Introduction The relationship between dinosaur carcasses and isolated theropod teeth is well known in the fossil record. The usual explanation is that theropod dinosaurs fed on the herbivore carcass. Other evidence is provided by theropod tooth marks on the surface of herbivore skeletal remains. In this work we study isolated theropod teeth and the tooth marks in evidence on the bones of the sauropod from El Oterillo II (Salas de los Infantes, Spain, Lower Cretaceous). Theropod and crocodylomorph teeth have been found in relationship with the sauropod carcass. The fossils lie on channel lag deposits composed of sandstones with quartzite gravel. Materials and methods Thirty theropod teeth have been studied using qualitative features, statistical and cladistics analysis in addition to the tooth marks present on the vertebrae. Results The morphology of the theropod teeth has revealed greater palaeobiodiversity in these faunas than previously known, including baryonychine spinosaurids, basal tetanurans, dromaeosaurids and a singular coelurosaurian. The presence of tooth marks and isolated theropod teeth in close relationship with the sauropod carcass could also provide new evidence of the scavenging of theropod dinosaurs on the sauropods of this age and location. Conclusions Six morphotypes of theropod teeth have been distinguished; the combination of basal and derived tetanurans is congruent with the known record from the Early Cretaceous of the Iberian Peninsula. The most probable explanation for the association of isolated theropod teeth and sauropod remains is the scavenging of the carcass by theropod dinosaurs.