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Re: Science feather strength debate



On 11/1/2010 11:28 PM, Tim Williams wrote:
> It could have; but any such flight stroke would be
> rudimentary.

Yes. But then, they were rudimentary birds, were they not? You have to start somewhere, and it does not seem unlikely in principle that the very first "bird" that could generate thrust or lift w/ a downstroke was not capable of a full upstroke as outlined by Mike H.

> _Confuciusornis_  would have to wait for a breeze of the right
> magnitude and direction in order to pull off this "soar".

Erik makes an excellent point in that some environments the "breeze" is *always* there. No waiting. These environments may be limited in area, but exist in evolutionarily significant time frames.

There is a very high probability that gliding species adapted to (as example) a forest environment were fortuitously exposed on a daily basis (in mid-flight!) to such conditions over the course of the planet's history.

Assuming a lack of previously established competition, the result might well be a creature that (perhaps having previously evolved the capability of "locking" it's "wings" to support it's weight while gliding) had a limited range of motion relative to an upstroke.