Ornithopod diversity in the Lower Cretaceous of Spain: New styracosternan remains from the Barremian of the Maestrazgo Basin (Teruel province, Spain)

Abstract

New material of an iguanodontid styracosternan ornithopod from the Lower Cretaceous of the Iberian Peninsula is described. The cranial and postcranial skeletal remains are from the Barranco del Hocino-1 site. These fossils (Iguanodontidae sensu Xu et al., 2018) represent the first medium-sized styracosternan from the Upper Sequence of the Blesa Formation (Barremian). The new material is characterized by a unique combination of characters that suggest they correspond to a new taxon: the first caudal vertebra with a ventral keel, the ilium with the preacetabular process twisted along its long axis, the dorsal surface of the preacetabular process and the main body totally straight and slender, the dorsal surface above the ischiadic peduncle slightly swollen but not forming a bulge or everted rim over the main body, and the ventral surface of the ischiadic peduncle and the postacetabular process straight and parallel to the dorsal surface of the main body. The new material is part of a vertebrate fossil assemblage of disarticulated bones but it represents the most anatomically informative remains of an styracosternan of the Oliete subbasin and would be potentially a distinct taxon. Regarding the new material along with the seven known taxa, the fossil record from the Barremian of the Iberian Peninsula depicts the existence of great diversity and abundance of ornithopod dinosaurs during the Early Cretaceous in the southwest of Europe, indeed greater than in other regions and thus aiming to be a relevant paleogeographic scenario for the evolutionary history of the group.