Systematic study of the historical material of Upper Cretaceous reptiles from the Tremp Basin (Catalonia, Spain) housed at the Museo Nacional de Ciencias Naturales (Madrid)

[Purpose]: The development of the studies on Mesozoic reptiles of the Spanish record occurred much later than in several European countries such as United Kingdom, France or Germany. Thus, very scarce and punctual findings were performed in the second half of the 19th century, followed by the work of José Royo y Gómez, which was stopped by the Spanish Civil War. The professional surveys and studies carried out in the 1950s in the Upper Cretaceous levels of the Tremp Basin (Lleida, Catalonia, Spain) can be considered as the origins of the development of this discipline in Spain. The works in the Tremp Basin were performed through the collaboration of national and foreign researchers. The Spanish palaeontologist Emiliano Aguirre and the French Albert Félix de Lapparent published some preliminary notes on the vertebrate fauna identified there. However, no detailed systematic study of these historical remains was ever done.[Methods]: The unpublished historical remains from the Tremp Basin collected by Aguirre and Lapparent, and preserved in the Museo Nacional de Ciencias Naturales (Madrid) collections, are studied here.[Results]: The analysis of unpublished historical documentation housed in the archive of that institution allows us to improve the knowledge about the history of these findings, as well as to recognize the precise sites from which each of these fossils come.[Conclusion]: The systematic study of these specimens, corresponding to turtles, crocodiles and dinosaurs, is performed here. They are attributed to Bothremydidae indet., cf. Pan-Cryptodira, cf. Allodaposuchidae, Titanosauria indet., Nodosauridae indet. and Ornithopoda indet.This research is funded by the Ministerio de Ciencia e Innovación (CGL2015-68363-P).Peer Reviewe