Here's what happens when you delete all members of the Lepidosauromorpha from the present reptile tree except the basal pterosaur MPUM 6009 and two turtles.
At far left, Ichthyostega is the outgroup taxon and the turtles nest with it. Pterosaurs nest at the base of the Sauropterygia.
At near left, three specimens of Gephyrostegus form the outgroup. Pterosaurs and turtles nest at the base of the Sauropterygia.
At near right, several non-reptiles form the outgroup taxa. Turtles nest with Eocaecelia while pterosaurs nest at the base of the Sauropterygia.
At far right, no outgroups were employed. Pterosaurs nest with turtles as an outgroup to the Archosauromorpha with a shift of branches that brings the Sauropterygia to the base of the tree.
Given the opportunity, pterosaurs nest with turtles and basal sea reptiles rather than archosaurs and archosauromorphs. Taxon exclusion was responsible for this!