Re: Confuciusornis sanctus

["Patrick Norton" <ptnorton@email.msn.com>]

>So the large claw on the first digit of the hands of C. sanctus was a sort
of an alulua?<

I'd say (in _C_ anyway) that the claws of digits I and III were capable of
serving that function, since they both appear capable of being extended and
elevated above the plane of the wing. It is my belief (so far just
speculation since it hasn't been tested) that the claws in that position
would have functioned aerodynamically in a manner very much like an alula.
The movements of digit II, with it's primary feathers, was probably not
involved in that function but more likely involved only in the flight
stroke, which probably explains why the claw was already becoming reduced.

> I'd known that the alulua replaced the finger in form (the latter evolving
into the former), but not in function.<

One did not evolve into the other.  Their function was analogous, but they
are clearly different structures.  The nub of my hypothesis is that both
performed the same aerodynamic 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?<

I wish I knew. As I mentioned before, some wind tunnel tests on some models
might help with such questions........

Pat