Ornithostoma sedgwicki – valid taxon of azhdarchoid pterosaurs

Abstract

Ornithostoma sedgwicki Seeley, 1891 from the Lower Cretaceous (Albian) Cambridge Greensand of England is represented by edentulous jaw fragments, posterior skull fragment with the supraoccipital crest, and by several postcranial bones attributed previously to Lonchodectes. Ornithostoma is referred to the Azhdarchoidea based on a combination of derived characters (teeth absent, middle cervicals moderately elongated, pneumatic foramen on anterior side of humerus, large pneumatic foramen on posterior side of femur at greater trochanter) and plesiomorphic characters (deltopectoral crest not warped, femoral neck to shaft angle less than 145°). The structure of the supraoccipital crest and humerus resembles those in Tapejara, but Ornithostoma differs from that taxon by a strong median ridge on the occiput presumably associated with a more elongated rostrum. At least three taxa of basal azhdarchoids were present in the British Lower Cretaceous.