A New Rebbachisaurid Sauropod from the Isle of Wight.

The type genus of the Rebbachisaurids, Rebbachisaurus was a sauropod, big plant-eating dinosaur similar to the famed Diplodocus, and member of the Diplodocoidea superfamily. It lived during the Early Cretaceous in what is now North Africa. It was first described in 1954 by R. Lavocat from fragmentary remains, consisting of a tail vertebra, a humerus (upper arm bone), a scapula (shoulder blade) and a sacrum, and collected from the Tegana Formation of Morocco. The species name is Rebbachisaurus garasbae. In 1960, A.F. de Lapparent described a second species, R. tamesnensis from various fragments of the Farak Formation of Niger, but this one is a bit dubious and can well belong to a completely different sauropod. More complete material from the Rio Limay Formation of Argentina including a partial skull has been referred to a third species, R. tessonei (Calvo & Salgado, 1995), and was used as proof of a land connection between Africa and South America in the Early Cretaceous, but the species has since been transferred to its own genus, Limaysaurus. So as today, the only species referable with certainty to the genus Rebbachisaurus is the Moroccan one described by Lavocat.

Besides Africa and South America, Rebbachisaurids were also living in Europe. The species Histriasaurus boscarottii, has been erected based on a few vertebrae from the Early Cretaceous (Hauterivian-Barremian) of Croatia (Dalla Vecchia, 1998), the most ancient member of the family so far and some materials from the Castrillo de la Reina Formation (Barremian-Aptian) of Spain have been reported by Pereda Superbiola et al. in 2003 and recently described in details under the name Demandasaurus darwini by Fernández-Baldor et al., in 2011. Finally, rebbachisaurids are also known from the Isle of Wight of England. A characteristic scapula (shoulder blade) collected by Nick Case in 1989 from the Wessex Formation on the southwest coast of the Isle of Wight has been described by Philip Mannion in 2009. In a recent cladistic analysis by Carballido et al., (2010), this British scapula comes, oddly, as a sister taxon of the South American Limaysausus tessonei. It is possible that the newly described caudal vertebra does belong to the same animal, even if the phylogenetic analysis placed it in a close kinship with the Spanish Demandasaurus and the African Nigersaurus, rather than with Limaysaurus. However, conclusions based on single incomplete bones are probably not to be entirely trusted until new discoveries are added to the analysis.