Check out the detailed color drawing of the Tapejara imperator - mid
cretaceous pterosaur from Brazil at:

http://www.johnsibbick.com/about.asp click on the right picture

Seems they have found a pterosaur with an even larger sail, 25' tall
with a wingspan of over 40'.

The fossels clearly show the sails covered with fine hair. Many think
they sailed along the coast rarely needing to flap for forward
movement. Also interesting is the wings and sail had a layer if super
thin veins and muscle that would shape the sail and wings.

Could this be the the future of sails?

Joe