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Re: Science feather strength debate
Erik Boehm <firstname.lastname@example.org> wrote:
> If you can power the downstroke, the upstroke (back to horizontal) should
> take care of itself, what am I missing?
Apparently the humerus must be lifted above the horizontal in order to
achieve a recovery stroke. This is according to Rayner (in the Ostrom
Symposium Volume) although this is not the only source.
> The presence of a keel, indicates the forelimbs were doing something that
> required more power than could be delivered without the keel.
BTW, although _Confuciusornis sanctus_ (the type species) has a keel,
other confuciusornithids (such as _C. dui_, _Changchengornis_ and
_Eoconfuciusornis_) do not.
> When your forelimbs are elongated with small claws, but covered in long
> aerodynamic feathers, and your descendants use the keel and forelimbs for
> flapping, it
> seems simplest and logical to assume the most likely reason for the keel, was
I take your point. However, it now appears that many elements of the
flight apparatus arrived by a process of exaptation. In other words,
they original had other (non-flight) functions, and took on a role in
Maybe the expanded pectoral muscles were used to help _Confuciusornis_
climb up tree trunks? After all, the hindlimbs were poorly adapted
for climbing, so the forelimbs might have been forced to do most of
> If it had all these flight adaptation, but yet still was incapable of powered
> flight.... what were those adaptations for? that seems like an awful lot of
> adaptation for
> gliding between trees
That's assuming it glided between trees. Maybe _Confuciusornis_
glided from trees down to the shore, or into shallow water?