In 1882, Karl Zittel described a wing from Rhamphorhynchus gemmingi. This specimen is now in the Bayerisch Staatssammlung, München, Germany. It is a very fine specimen of a single wing with the patagium (wing membrane) intact. The quality of the fossil is so fine that the membrane structure can be determined with a high degree of confidence.
Zittel's wing is a very important fossil which can shed light on the nature of the Pterosaurian wing structure.
On examination, the membrane is seen to be supported with a vast number of fine, parallel fibres. These structures would give the wing edge its support and allow the wing to fold evenly when relaxed. They probably also limited damage due to tearing of the membrane and allowed healing to take place.
There is no evidence of hair on this wing and it is unlikely that Pterosaurs were hairy. The one specimen that appeared to be a hairy pterosaur was Sorder pilosus. In the light of modern research by David Unwin and Natasha Bakhurina, it seems that the hair like structures in Sordes are likely to be fragmented wing membrane fibres.
Bakhurina N.N. & Unwin D.M.; 1995, A prelimninary report on the evidence for 'hair' in Sordes pilosus, an Upper Jurassic pterosaur from Middle Asia. (In: SUN A.& WANG Y., Sixth Symposium of Mesozoic Terrestrial Ecosystems and Biota), China Ocean Press, Beijing, pp. 79-82
Photographs of the original Zittel specimen taken in 1987.