The development of the pterosaur wing to the bird wing requires fewer changes than one might think due to "facilitated variation".
http://www.pnas.org/content/104/suppl_1/8582.full
"The adaptability and robustness of normal muscle, nerve, and vascular development have significant implications for evolution, for these processes accommodate to evolutionary change as well. In the case of the evolving wing, if bones undergo regulatory change (driven by genetic change) in length and thickness, the muscles, nerves and vasculature will accommodate to those changes without requiring independent regulatory change. Coevolution is avoided. Selection does not have to coordinate multiple independently varying parts. Hence, less genetic change is needed, lethality is reduced, larger phenotypic changes are viable, and phenotypic variation is facilitated." (John Gerhart and Marc Kirschner 2007)
I'm confused. I was under the impression this blog was going to make the case that birds descended from pterosaurs and yet everything you post shows clear support that birds descended from dinosaurs. It doesn't really make much sense.
ReplyDeleteCould you explain why you say that please?
ReplyDeleteIt looks like Pandora dawn may not be returning.
ReplyDeletePerhaps he (she) read the material again and decided it did actually make sense.