Here is some significant information about the pterosaur wing . (I will elaborate in further posts).
"The soft tissue preserved in the holotype (IVPP V12705) of Jeholopterus ningchengensis [pterosaur] from the Daohugou Bed (Late Jurassic or Early Cretaceous) of China is described in detail. The plagiopatagium can be divided into the distal, comparatively more rigid actinopagatium and a proximal, more tensile tenopatagium. The actinopatagium extends from the wing finger to the articulation between the humerus and the forearm, and shows the presence of at least three layers containing actinofibrils. In each layer, the actinofibrils are parallel to subparallel, but this direction diverges from layer to layer. When distinct layers of actinofibrils are superimposed (owing to taphonomic compression), a reticular pattern is generated. The presence of layers with differently oriented actinofibrils is widespread in this pterosaur. A well-developed integumental covering formed by fibres (here named pycnofibres) that are thicker than the actinofibrils is present. Ungual sheaths that extend the length of the pedal and manual claws of this taxon are also observed. Although the understanding of the mechanical properties of the wing membrane is hampered by the lack of knowledge regarding the composition of the actinofibrils, the configuration observed in Jeholopterus might have allowed subtle changes in the membrane tension during flight, resulting in more control of flight movements and the organization of the wing membrane when the animal was at rest."
"closer to the body (the tenopatagium), was extensively covered by elongated and thick fibres here called pycnofibres."
"The pycnofibres are further formed by smaller fibrils of unknown nature."
(Alexander W. A. Kellner1,*, Xiaolin Wang2,*, Helmut Tischlinger3, Diogenes de Almeida Campos4, David W. E. Hone2 and Xi Meng2,5)
For details see page 324 (PDF page 3) etc of the actual article which is a PDF, obtainable at
Soft tissue of J. ningchengensis (IVPP V12705). (a) Details of the actinopatagium with different layers indicated by white arrows (top slab). (b) Actinopatagium under ultraviolet light showing the difference between the actinofibrils and the integumental covering (dark colour). (c) Tip of the wing membrane associated with the fourth phalanx of the right wing finger. (d) Ungual sheaths of the right manual digits indicated by black arrows. Scale bars: (a–c) 1 mm; (d) 10 mm. acpt, actinopatagium; f-B, fibres type B; inc, integumental covering; laf, different layers of actinofibrils; maf, merging actinofibrils; ph2d4, second phalanx of the wing finger; ra/ul, radius and ulna; us, ungual sheaths.