https://books.google.co.uk/books?id=KG86AgWwFEUC&pg=PA454&dq=patagial&hl=en&sa=X&ei=AzRBVendC9DLaOehgMgC&ved=0CCoQ6AEwAg#v=onepage&q=patagial&f=false
This shows that feathers in basal Paraves are not exaptations.
Flight feathers are not variants of thermal insulating material, but structures that have evolved over a long period, enabling the span and aspect ratio of the wings to be progressively increased as they developed.
The structure of a flight feather is dedicated wholly to withstanding the bending and torsional moments caused by aerodynamic forces, and delivering these moments through the follicle to the wing skeleton.And:
The main features of the hypothetical patagial glider can still be seen, albeit much modified, in the modern bird wing, which has a patagium that joins the side of the body to the elbow joint, and continues as a narrow strip along the posterior side of the ulna, and of the reduced hand skeleton.