and required no additional development. See this link for more details about the actinofibrils: http://pterosaurnet.blogspot.com/2011/10/bird-feathers-are-analogous-to-wing.html http://en.wikipedia.org/wiki/Flight_feather "Remiges (from the Latin for "oarsman") are located on the  posterior  side of the wing.  Ligaments  attach the long calami, or quills, firmly to the wing bones, and a thick , strong band of  tendinous  tissue