The pterosaur assemblage of the Oxford Clay Formation (Jurassic, Callovian–Oxfordian) from the UK

Abstract

AbstractThe Middle–Upper Jurassic Oxford Clay Formation of the UK is a highly productive fossiliferous unit, containing numerous fossils of marine and terrestrial vertebrates. Despite this abundance, pterosaurs make up only a tiny percentage of the assemblage. There are currently only seven specimens accessioned in the Oxford University Museum of Natural History and Natural History Museum, London. Of these, only one specimen (an association of material from a juvenile animal) has been named, identified as Rhamphorhynchus jessoni. Following a detailed examination, it is identified here as lacking any autapomorphies and the species R. jessoni is considered a nomen dubium. The other Oxford Clay Formation pterosaur fossils are similarly identified as indeterminate, except for an isolated scapulocoracoid which is positively identified as Rhamphorhynchus sp. The rarity of pterosaurs is attributed to a combination of the fragility of their bones and the tendency of volant animals to have low population densities at sea.