It has been argued that "Dimorphodon" was a biped, though fossilised track remains of other pterosaurs (ichnites) show a quadrupedal gait while on the ground--but these are all of derived pterosaurs with a short 5th toe.
It has been argued that "Dimorphodon" was a biped due to its relatively well developed hindlimbs and characteristics of its pelvis. Although these traces are all of derived pterosaurs with a short 5th toe.