New sauropod appendicular remains from the Upper Cretaceous of Romania: Accessing the morphological variability

Abstract

The Upper Cretaceous sauropod fossil record from Romania is abundant, mostly originated from the Maastrichtian deposits of the western-southwestern margin of the Transylvanian Basin, and in the Hațeg and Rusca Montană basins. Most specimens were found in isolation or in low degree of association and only few partial skeletons have been reported. The presence of at least four taxa was recently considered, including three defined forms: Magyarosaurus dacus, Paludititan nalatzensis and “Magyarosaurus” hungaricus. However, the phylogenetic affinities of these taxa within Lithostrotia are still under debate. A large sample of appendicular remains, predominantly composed by unpublished specimens, is described here in detail to provide new data about the diversity of the sauropods of the Hațeg Island during the Maastrichtian. All specimens show affinities or are compatible with lithostrotian sauropods, even if the availability of characters of some of them does not allow its attribution to this clade. Five morphotypes for the femora, three to four for the humeri, three for the fibulae, and two for the radii, ulnae, manus, pubes, ischia, tibiae, and pedes are established, supporting the presence of four or five taxa in this domain. A unique partial manus morphology characterized by its extreme gracile metacarpals is reported, only surpassed by an unpublished manus found in the Spanish Lo Hueco fossil-site (late Campanian-early Maastrichtian), suggesting that a titanosaurian lineage with extremely elongated manus inhabited the European realm, in both Hațeg and Ibero-Armorican islands, at the end of the Mesozoic.