A rebbachisaurid sauropod from the Lower Cretaceous of the Isle of Wight, England

Rebbachisauridae is one of the most enigmatic and poorly understood clades of sauropod dinosaurs. They are considered to be basal diplodocoids, are known solely from the Cretaceous (Hauterivian-Coniacian), and have only been recovered from Africa, South America, and Europe. As a result of their extreme skeletal reduction, rebbachisaurid material is highly susceptible to destructive taphonomic processes and thus most remains are highly incomplete and fragmentary. Previous remains attributed to rebbachisaurids from England are restricted to isolated teeth. Here a sauropod scapula from the Lower Cretaceous (Barremian) Wessex Formation of the Isle of Wight, England, is described. Although incomplete, this scapula possesses both the extreme dorsoventral expansion of the scapular blade and the “hook”-like acromial process that are characteristic of rebbachisaurids. This study has also enabled the recognition of a putative local synapomorphy of Rebbachisauridae, with the highest point on the dorsal margin of the scapula blade equal to or exceeding that of the dorsal margin of the proximal plate. This scapula is one of the oldest known examples of a rebbachisaurid and represents the first postcranial remains of this clade to be described from the United Kingdom. In addition, it provides further support for the presence of rebbachisaurids in the Early-mid Cretaceous of Europe.