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RE: Combined answer Archaeopteryx running...
Jim Cunningham wrot:
> > However, at a certain point (probably early in the Pygostylia) it
> > became advantageous to dedicate the manus and carpus to flight, so
> > both were absorbed into the wing.
> Then why did pterosaurs retain the manus all the way to the K/T?
The long fingers of pterosaurs supported the wing. Also, we don't have the
pterosaur equivalent of _Archaeopteryx_ to establish what changes the manus
did go through in early pterosaur evolution. Did the immediate ancestors of
the Pterosauria retain a prehensile manus, or was it absorbed into the
flight surface from the get-go?
> I would agree that they are inferior to SOME pygostylians.
I would say _Archaeopteryx_ was aerodynamically inferior to MOST
pygostylians - living and extinct. I don't even think Archie's flight
capabilities were adequate even for hunting on the wing.
> But I suspect they were quite adequate for the use the animals actually
> put them to.
Definitely. Although Archie looks ungainly and primitive compared to modern
birds, it was a marvel of evolution - and not just from a teleological
context. The development of wings opened up a universe of possibilities for
small coelurosaurian hunters.
> And some pygosylians have flight capabilities inferior to
>This is the point I've been trying to make, with the exception that I
>don't believe archie's anatomy was particularly conservative.
I DO believe Archie's anatomy was conservative - at least osteologically.
Again, I think Ostrom is spot-on. Stripped of its feathers, one would be
hard put recognizing _Archaeopteryx_ as a flighted bird. The skeleton of
Archie is that of a rather unspecialized maniraptoran. The feathers, of
course, are a whole different story...
> And the lack of a hand precluded the later pygostylians from some
> grasping maneuvers. One life style is not inherently 'better' than the
Agreed - and I was careful to include both these points in my last post
(though I think you expressed it much better than me).
Timothy J. Williams
Iowa State University
Ames IA 50014
Phone: 515 294 9233
Fax: 515 294 3163