Revision of the theropod dinosaur Camarillasaurus cirugedae from the Early Cretaceous (Barremian) of Teruel province, Spain

Camarillasaurus cirugedae is a medium- to large-sized theropod taxon based on fragmentary remains of a single specimen from the Barremian site of Fuente Arnar in Camarillas (Teruel, Spain). It was initially interpreted as a representative of Ceratosauria, making it a taxon “outside time and space”. We revise the material that was originally assigned to Camarillasaurus as well as new fossil remains (surangular/articular, partial mid-caudal vertebra, femur, pedal ungual, partial tooth) from the type locality. The taxon can be diagnosed on the basis of a marked, rugose lateral tubercle on the surangular lateral to the mandibular glenoid, transversely concave dorsal prezygapophyseal articular surfaces, distally anteriorly flexed mid-caudal neural spines, and posteriorly extended distal caudal postzygapophyses that are connected to the neural spine by a bony web. Phylogenetic analysis identifies Camarillasaurus as a member of the Spinosauridae. Furthermore, it is morphologically different from the other named spinosaurid taxa from the Iberian Early Cretaceous (Vallibonavenatrix, Iberospinus, Riojavenatrix) demonstrating the high diversity of this group at that time. Phylogenetic analysis also indicates that Iberospinus, Vallibonavenatrix, and Camarillasaurus represent spinosaurines within the Spinosauridae, in contrast to the diverse contemporaneous baryonychines in England. Isolated spinosaurid remains, especially isolated teeth, are relatively abundant in the Hauterivian-Aptian of the Iberian Peninsula. Many of these remains, including the holotype of Camarillasaurus, have been found in continental facies such as alluvial plains, suggesting that these taxa may have had less aquatic affinities than has been proposed for the spinosaurs of the end of the Lower Cretaceous and the beginning of the Upper Cretaceous.