High sauropod diversity in the upper Barremian Arcillas de Morella Formation (Maestrat Basin, Spain) revealed by a systematic review of historical material

Purpose and methods Since the second half of the 19th century, the Arcillas de Morella Formation (late Barremian) has yielded abundant vertebrate fossil material from several outcrops of the Morella region (Maestrat Basin, Castellón, eastern Spain). Several historical specimens of fossil reptiles, so far unpublished or not studied in detail, are housed in the Museo Nacional de Ciencias Naturales in Madrid (Spain). In fact, many of the first dinosaur specimens discovered in Spain, from Morella, are part of the vertebrate palaeontology collection of that institution. Herein, this sauropod material is described and discussed in order to study the diversity of the sauropod fauna during the late Barremian on the Maestrat Basin. Results The specimens include both axial and appendicular elements. The systematic study of this material suggests the presence of indeterminate titanosauriforms, some of which have somphospondylan and ‘laurasiform’ affinities. Comparative analysis of two isolated humeri from Morella (MNCN 59703 and MNCN 68484) and a humerus subsequently found in this area, indicates the presence of three titanosauriform taxa in the upper Barremian of the Maestrat Basin, two of which have somphospondylan affinities. Conclusions The sauropod diversity of the Arcillas de Morella Formation recognized herein, in particularly considering the titanosauriforms, is greater than that previously considered, at least three taxa.