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Re: Science feather strength debate



Erik Boehm <erikboehm07@yahoo.com> wrote:


> Sort of like hugging the tree tight to get a grip? Do we have any other 
> example of something like that? seems to me that squirrels can sufficiently 
> grip trees, without
> prehensile hands, or a keel.


Yeah... but squirrels are quadrupedal mammals with mobile wrist and
ankle joints.

Basal birds, like non-avian theropods, were not built for climbing.
Cursorial bipeds with wrists and ankles only capable of movement in a
single plane; long inflexible fingers; no specialized perching foot...

If confuciusornithids did climb, then they would have had to clamber
up trees using all fours.  (No, I don't buy the WAIR hypothesis -
especially if confuciusornithids could'nt elevate the humerus above
the dorsum.)  If the forelimbs played a major role in pulling them up
trunks, then extra pectoral musculature could have helped.  I'm not
saying that this is why _Confuciusornis_ had a keel.  But I would
hesitate to assume it was associated with execution of a flight
stroke.  It could have; but any such flight stroke would be
rudimentary.


> From what I gather, the manus doesn't exactly look adapted for getting a good 
> grip either, does it?

No, dead right.  And nor does the foot.  But at least the hallux is
lower down on the foot compared to the primitive theropod condition.


> It seems to me, that it has more than enough adaptations to allow it to ridge 
> soar in conditions presently found in many places.

_Confuciusornis_ would have to wait for a breeze of the right
magnitude and direction in order to pull off this "soar".  Until that
happens, the poor bird is stuck on the ground whistling Dixie...   ;-)


Cheers

Tim