The integrative patagial morphology of Draco volans was examined to elucidate the possible evolutionary pathway of origin of active patagia in the flying dragons and in extinct taxa that are thought to have possessed similarly constructed flight membranes. The area of the patagia and accessory aerodynamic surfaces is compared between Draco volans and Ptychozoon kuhli, a gekkonid with passive patagia. Comparisons of patagial area are also made between selected species of Draco. Scale architecture of the patagium of Draco is described and is related to pertinent aspects of the structure and properties of the integument. The relationships of these characteristics to the morphology of the ribs and their related musculature are emphasized. The overall assessment of these features in relation to patagial form is employed to develop an evolutionary scenario for the origin of active patagia.