The phylogenetic position of the Pterosauria within the Archosauromorpha re-examined

A previous analysis of the phylogenetic position of the Pterosauria argued that pterosaurs were not closely related to dinosaurs as is generally accepted, but rather were outside the crown group Archosauria. However, that study was dismissed for the use of inappropriate methods. Here, the data set from that analysis was divided into five partitions: one with characters associated with cursorial digitigrade bipedal locomotion and the other four with characters from the skull and mandible, postcranial axial skeleton, forelimb and hindlimb, respectively. The partitions were subjected to homogeneity testing, and the Cursorial partition was found to be incongruent with other partitions and all other characters at the α = 0.01 probability level. Deletion of the Pterosauria removed all significant incongruence, demonstrating that the incongruence results from the coding of pterosaurs for the cursorial characters. The cause of the incongruence was interpreted as homoplasy in hindlimb morphology, and after re-evaluating and reformulating the characters of the Cursorial partition, the revised data set was tested for homogeneity and no significant incongruence was found. Lastly, the data set was updated with additional characters and taxa from recent analyses, tested as before, and when analysed suggested that the Pterosauria were basal archosauriforms well outside the crown group Archosauria.