A spinosaurid from Thailand (Sao Khua Formation, Early Cretaceous) and a reassessment of Camarillasaurus cirugedae from the Early Cretaceous of Spain

Abstract

ABSTRACT We report theropod caudal vertebrae found at Phu Wiang Mountain, Thailand. They resemble the Portuguese Baryonyx and pertain to the Spinosauridae based on the presence of striations on the surface of the transverse process of the caudals, well developed double keels and a deep ventral groove on the centra, two laminae, delimiting three fossae below the transverse process, and posterior caudals having curved, rod-like neural spines with small process at the base. This supports the presence of spinosaurids in the Sao Khua Formation of Thailand. Furthermore, the putative basal ceratosaur Camarillasaurus Sánchez- Hernández and Benton, 2014 from Spain is found here to be a spinosaurid based on the resemblance of the type materials to the Thai spinosaurid described in the present work, as well as the phylogenetic analysis and the similarity to other spinosaurids. In Europe, spinosaurids have been reported from England, Portugal, and Spain. The reassessment of Camarillasaurus adds to the number of this group in this region. The presence of more than one spinosaurid taxon in the same region is common and can be found in the Kem Kem Beds of Morocco, the Araripe Basin of Brazil, the Iberian Peninsula, and the Khorat Plateau of Southeast Asia.