Morphological and functional differences between rhamphorhynchoid and pterodactyloid pterosaurs with emphasis on flight

Abstract: To explain how the morphological differences between Rhamphorhynchoidea and Pterodactyloidea affect flight performances and life styles wings and claws of pterosaur fossils from collections in Uppsala and Munich have been measured. The measured specimens are from Jurassic limestones and shales in Solnhofen, Eichstätt and Holzmaden and include Dorygnathus, Campylognathoides, Rhamphorhynchus, Anurognathus, Pterodactylus, Germanodactylus and Gallodactylus. The measurements indicate differences between Rhamphorhynchoidea and Pterodactyloidea in wing construction and length of the claws. Different wing construction requires different flight performance. The shorter innermost part of the wing in Rhamphorhynchoidea indicates flapping flight while the longer innermost part of the wing in Pterodactyloids indicates soaring. Calculation on the narrowness of the wing has been done on three different specimens of Rhamphorhynchus, demonstrating a narrow distal part of the wing that probably was wider towards the body. Variation and divergence from the general morphological pattern creates diversity within both suborders, which results in three different flight performances in Rhamphorhynchoidea and two different flight performances in Pterodactyloidea. The three different flight performances proposed for Rhamphorhynchoidea are (1) Mixed gliding and flapping flight with broad wings, (2) Flapping flight with narrow wings and (3) Flapping flight with elliptical wings. The two different flight performances proposed for Pterodactyloidea are static and dynamic soaring. Measurements of the length of the claws indicate that the claws of the finger and toes were of the same size in Pterodactyloidea while the claws on the fingers were longer than the claws of the toes in Rhamphorhynchoidea, indicating tree climbing. Soaring flight, morphological characteristics similar to these in birds as well as development of hollow bones are all indications that pterosaurs probably had air sacs that were primitive in Rhamphorhynchoidea but well developed in Pterodactyloidea.