Monograph: New material of Valdosaurus canaliculatus (Ornithischia: Ornithopoda) from the Lower Cretaceous of southern England

Until recently, the Wealden ornithopod dinosaur Valdosaurus canaliculatus (Galton, 1975) was known only from the holotype femora and a set of unassociated referred postcranial specimens. All of this material has been recovered from the Wessex Formation (Barremian) of the Isle of Wight, UK and the Grinstead Clay Member (middle–upper Valanginian) of West Sussex, UK. Here, we provide a detailed description of four additional associated specimens from the Isle of Wight that include almost complete hindlimbs, as well as associated pelvic and axial elements. These new finds substantially increase the amount of material available for the taxon and allow the first definitive associations between the diagnostic femora and other elements of the skeleton. Comparisons with dryosaurid taxa and contemporary Wealden ornithopods indicate that Valdosaurus can be distinguished by a unique combination of femoral character states. Phylogenetic analysis supports the monophyly of Dryosauridae and indicates that Valdosaurus forms a clade with Elrhazosaurus and Dysalotosaurus to the exclusion of Dryosaurus. It is likely that Valdosaurus was more abundant in Wealden faunas than has generally been assumed.