The largest ornithopod (Dinosauria: Ornithischia) from the Upper Jurassic of Europe sheds light on the evolutionary history of basal ankylopollexians.

Ankylopollexia was an abundant and diverse clade of ornithopods present in North America, Europe, Africa, and Asia from the Late Jurassic to the Late Cretaceous. However, the relationships between the basal ankylopollexians are poorly understood. A new ankylopollexian ornithopod genus and species is described here, based on a dentary tooth, an ungual pollex of the manus, and an almost complete left hindlimb. The fossils come from deposits of the Villar del Arzobispo Formation (upper Kimmeridgian–Tithonian). Phylogenetic analysis revealed that Oblitosaurus bunnueli gen. et sp. nov. is the basalmost member of Ankylopollexia, together with Draconyx loureiroi. Furthermore, these results have relevant taxonomic implications for the genus Camptosaurus , being the first phylogenetic analysis to support the monophyly of Camptosaurus species. The estimated size of Oblitosaurus bunnueli suggests that it is the largest ornithopod described in the Upper Jurassic of Europe and one of the largest around the world, and could be the trackmaker of large ornithopod tracks found in the Upper Jurassic of the Iberian Peninsula. This discovery increases the known ankylopollexian diversity in Iberia, revealing the presence of an Iberian basal ankylopollexian clade that does not appear to be present in the contemporaneous outcrops of North America. [ABSTRACT FROM AUTHOR]