A giant spinosaurid from the Iberian Peninsula and new data on the Early Cretaceous Iberian non-avian theropod palaeodiversity

Abstract

Despite some exceptional cases, the Lower Cretaceous theropod record from Iberia mainly comprises isolated teeth and fragmentary skeletons. In the Cameros Basin, theropods have been mostly documented in the Eastern Cameros sub-basin with baryonychine spinosaurids dominating this sector. Instead, theropods are rarer in the Western Cameros sub-basin. Here, we describe material from the Western Cameros sub-basin, recovered in the upper Hauterivian–lower Barremian Golmayo Formation of Soria (Los Caños and Zorralbo I sites), which allowed us to identify three early-branching tetanuran and three baryonychine dental morphotypes, and a large-sized spinosaurid from Zorralbo I. The latter is represented by cranial, axial, and appendicular bones, and identified as a large-sized baryonychine based on anatomical and phylogenetic studies. Our results demonstrate that the theropod assemblages are consistent within the entire Cameros Basin, exhibiting a dominance of baryonychines. Western Cameros theropods are not only limited to Baryonychinae but they would also coexist with other early-branching tetanurans and coelurosaurians. The Lower Cretaceous Iberian record is represented by taxa from all major clades within Theropoda (i.e., Tetanurae, Allosauroidea, Carcharodontosauria, Coelurosauria, Ornithomimosauria, Paraves and Dromaeosauridae), being Spinosauridae the most prevalent group, with five described genera and species and a large number of tooth morphotypes. Indeed, three spinosaurine and ten baryonychine tooth morphotypes have been identified in the Iberian record so far. This study demonstrates that the entire Cameros Basin has a great representation of the theropod record of the Iberian Peninsula, and it underscores the potential of this basin to understand the Iberian palaeobiodiversity, especially in spinosaurids.