New titanosaurian caudal remains provide insights on the sauropod diversity of the Hațeg Island (Romania) during the Late Cretaceous

Abstract

ABSTRACT The Upper Cretaceous sauropod record from Romania is abundant, but mainly composed by isolated and poorly preserved specimens. They were found in Maastrichtian units cropping out in both the western-southwestern margin of the Transylvanian Basin, and in the Hațeg and Rusca Montană basins. Two small-sized taxa, Magyorasaurus dacus and Paludititan nalatzensis, were considered as valid; however, the presence of other forms is not ruled out. An important sample of sauropod caudal vertebrae is described in detailed to provide new data about the diversity of the sauropods of the Hațeg Island during the Maastrichtian. Distinct morphologies are recognized for the caudal vertebrae, including four morphologies for the anterior-most elements; at least three for the anterior and middle ones, and at least two for the posterior caudals, including sauropods with opisthocoelous condition. The possibility of four different tail morphologies is suggested, which might belong to four different taxa, including Paludititan nalatzensis, Magyarosaurus dacus (the material previously referred to it seems to be composed by more than one taxon) and two other species. A new character for morphological datasets describing the position of the intraprezygapophyseal lamina in the middle and posterior caudals is proposed, which may be characteristic of some European taxa.