It is problematic whether Pelorosaurus is a valid genus and if so, what its valid species are. Of the fossils the first species of Pelorosaurus, P. conybeari, was based on, a separately discovered humerus and vertebrae, the latter are the type specimen of the species and the former is seen as the holotype of the genus. Both specimens might not be of the same animal; furthermore, P. conybeari is a junior synonym of Cetiosaurus brevis. Many species have later been assigned to Pelorosaurus, most of which today are considered different dinosaurs. One later species still not having received a separate generic name, P. becklesi, is known from a sacrum, pelvis and limb fragments, as well as from skin impressions; it was covered in hexagonal scales.