Re: Confuciusornis sanctus

[dbensen <dbensen@gotnet.net>]

>>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.<<

That makes sense.  Having _both_ digits I and III as airfoils would make for
some interesting airflow patterns.  I wonder whether these birds could pull of
some maneuvers that modern birds cannot.

>>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.<<

??  Isn't the alula a modified digit I?

Dan