Pterosaur phylogeny and comments on the evolutionary history of the group

Abstract A cladistic analysis based on 39 terminal taxa and 74 characters (several multistate) using PAUP (Phylogenetic Analysis Using Parsimony) (3.1.1 for MacIntosh and 4.0b10 for Microsoft Windows) presents a new hypothesis of pterosaur inter-relationships. This study suggests that the most primitive taxon is the Anurognathidae, followed by Sordes and all remaining pterosaurs. Dendrorhynchoides is confirmed as a member of the Anurognathidae, being closely related to Batrachognathus. Preondactylus occupies a more derived position than Sordes , which questions its previous assignment as the most primitive pterosaur. The hypothesis of rhamphorhynchoid paraphyly is confirmed, with the Rhamphorhynchidae more closely related to the Pterodactyloidea than to more basal forms. The Pterodactyloidea shows a basal dichotomy: the Archaeopterodactyloidea and the Dsungaripteroidea. The Archaeopterodactyloidea is formed by Pterodactylus + Germanodactylus and a clade formed by Gallodactylidae + Ctenochasmatidae. The Nyctosauridae occupies the basal position within dsungaripteroids and is followed by the Pteranodontoidea and the Tapejaroidea. Pteranodontoids have Pteranodon at the base, followed stepwise by Istiodactylus, Ornithocheirus and the Anhangueridae. Tapejaroids are composed of the Dsungaripteridae at the base followed by the Tapejaridae and the Azhdarchidae. Major trends within pterosaur evolutionary history are: general increase in size (wing span and body); increase of wing metacarpal and pteroid; decrease of proportional length of the second and third wing phalanx relative to the first; gradual increase of rostrum (anterior to external nares); and anterior shift of the skull-mandible articulation. Cranial crests are present in most pterodactyloids, but markedly in the Ornithocheiroidea, where all taxa show some sort of crest on the skull. The loss of teeth, previously assumed to have occurred independently in several lineages, seems to be a general trend among dsungaripteroids. Several nodes recovered by this analysis are supported by very few characters, a result at least partially attributable to the limited available information from several taxa due to poor preservation and/or preparation.