Re: Arms into wings

[tsg94001@uconnvm.uconn.edu]

Thomas R. Holtz, Jr. said:
>
>However, the hands of _Archaeopteryx_ and even _Confusciusornis_ retained
>quite a bit of grasping ability (as various morphometric and morphological
>studies have suggested).  After all, there are few morphological differences
>between the forelimbs of Archie and dromaeosaurids.


I think what might be bothering many folks on this list (me included) is
the transitional phase. Ornithothoracines lost the grasping/predatory
ability of the wing (hence the carpometacarpal fusion).  Sure,
_Archaeopteryx_ and other non-ornithothoracines used their forelimbs for
both grasping and flying.  But how and why did the forelimb take on this
additional function of flight?  How did it begin?

I know this goes all the way back to Darwin and the Evolution of Incipient
Structures.  What good is half a wing, etc?  I'm not arguing against a
maniraptoran origin of birds - but for my own benefit what kind of changes
MAY have occurred in the design of the forelimb (especially externally -
i.e. feathers) between a non-flying basal "eumaniraptoran" and a flying
avian like _Archaeopteryx_?  There must have been a "not-quite-flying"
phase somehere in the middle, so what was the forelimb used for during this
stage?


Tim Williams