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RE: Evidence For a Feathered Velociraptor...



Michael Lovejoy wrote:

> Quill knobs will only appear where feathers need to be firmly anchored to
> resist external pressure; so when you see them on the forelimbs they
> normally indicate flight feathers. So you won't see evidence of feather
> attachment elsewhere on the skeleton, although a nicely preserved
> Microraptor himblimb could be interesting...
> It's been a while since I did anything on this subject, but IIRC the
> feathers don't actually reach the bone; the roughness / ridge/ knobs on the
> bone are caused by the tendons and muscles used to anchor the quills.
> This Velociraptor specimen seems like good evidence for GSP's secondary
> flighlessness thing - unless there's another reason for large, strongly
> attached forelimb feathers.


I think you may have answered your own question. :-)  If quill knobs only 
appear where feathers need to be firmly anchored to resist external pressure, 
then this expands the net wider to functions other than simply powered flight.  
WAIR and many other hypotheses posit that the proto-wings exerted aerodynamic 
forces in the lead-up to powered flight: drag, lift, thrust, or a combination 
of these.  So quill nodes might be an adaptation that preceded powered flight, 
and be associated with the need to have forelimb feathers firmly secured to the 
ulna during the incipient stages of flight evolution.

IMHO, the fact that _Velociraptor_ has quill knobs and clearly did *not* fly, 
adds an element of doubt to the idea that _Rahonavis_ was capable of powered 
flight because it had quill knobs too.  (I know the presence of quill knobs is 
not the only evidence in support of powered flight in _Rahonavis_, but it is 
one of the most compelling).  Also, the quill knobs of _Velociraptor_ (and 
maybe _Rahonavis_ too) may be associated with the need to securely anchor the 
forelimb feathers during prey capture.  In this case, the "external pressure" 
mentioned by Michael would be the struggling prey (e.g., _Protoceratops_).

So although the presence of quill knobs in _Velociraptor_ is certainly helpful 
to Greg Paul's 'neoflightless' hypothesis, it is not definitive proof.  Not 
yet, anyway.

Cheers

Tim
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