Theropod teeth from the upper Barremian (Lower Cretaceous) of Vadillos-1, Spain

The upper Barremian (Lower Cretaceous) palaeontological site of Vadillos-1 is located in the North of the Cuenca Province, Spain. It includes a sedimentary succession in "Weald" facies of brown and grey mudstones and red clays, corresponding to an alluvial-palustrine muddy floodplain. Among the collected fossils, there are several vertebrate remains belonging to theropod dinosaurs, including some teeth (VD1-197, VD1-178, VD1-179, and VD1-180) that are described and identified for the first time. The taxonomic assignment was approached following two methods beside the classical consideration of their overall morphology: a cladistic analysis performed on a tooth-based data matrix, and a discriminant analysis performed on a large dataset including measurements of non-avian theropod teeth. The DSDI > 1.2 and the braided enamel present seen in VD1-197 suggest that the specimen belongs to a Dromaeosauridae or a non-tyrannosaurid Tyrannosauroidea, but the cladistics analysis classifies this tooth in the latest. The analysis showed that VD1-178, VD1-179 and VD1-180 can be ascribed to Dromaeosauridae. The dental features characteristic of this clade and present in our specimens include a DSDI > 1.2, labial and lingual depressions, and a braided enamel surface texture, which allows to place these teeth more specifically within the Eudromaeosauria. The results show, for the first time, the presence of dromaeosaurids and possibly non-Tyrannosaurid Tyrannosauroidea at Vadillos-1, thus providing new data to the European Barremian record, and contributing to the updating the geographic distribution of these dinosaurs.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).