Re: Confuciusornis sanctus

[dbensen <dbensen@gotnet.net>]

>>I think that once feathered dinosaurs got into the air, aerodynamics became
the primary selective agent on wing design, including fingers and claws.<<

So the large claw on the first digit of the hands of C. sanctus was a sort of an
alulua?  I'd known that the alulua replaced the finger in form (the latter
evolving into the former), but not in function.  Does that mean that
Changchengornis (which has smaller thumb claws that C. sanctus) and C. dui
(which has even smaller thumb claws) flew differently than C. sanctus?

>>.  It may have been able to grasp with its hand, but my bet is that it
was not a very good at it because of the flight related modifications of
digit II.<<
Very possible.  The sheer rigidity of the flight feathers, if nothing else,
would have made bending digit II difficult.  However, that rigidity does not
precluded grasping with digit I, like bats do.  Also, if the claws are facing
inward (as they do in some species), that is, curving towards the chest, then
the bird can grip a large object (say, a tree), by "hugging" it.  There need not
be much strength or flex to digit II at all in this posture; digits I and
(maybe) III could hold up the bird's weight.  That stance would also be
convenient as a display of the primaries, perhaps part of a mating ritual.

Dan.