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Re: Evidence For a Feathered Velociraptor...
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.
> Can I ask by what process feathers come to leave quill knobs in bone? I
> wouldn't expect such a thing, because feathers are part of the integument,
> and replaced scales. Skin does not leave quill knobs in bone, and
> do scales, do they?
> Do only certain kind of feathers leave quill knobs in bone? Because
> have an awful lot of feathers to leave quill knobs, and what about parts
> the bird that have no bone underneath the feathers?
> Also, most birds molt their feathers on an annual basis; I'm trying to
> imagine the poor bird losing feathers from sockets in the bone and then
> growing new ones. Now, I know that pin feathers are sensitive, but...
> And do feathers only leave quill knobs on certain bones? What about rib
> spine bones; should these have quill knobs if the animal was completely
> covered in feathers?
> Dora Smith
> Austin, TX
> ----- Original Message -----
> From: "Guy Leahy" <email@example.com>
> To: <firstname.lastname@example.org>
> Cc: <email@example.com>
> Sent: Thursday, September 20, 2007 8:01 PM
> Subject: Re: Evidence For a Feathered Velociraptor...
> > As the authors note, the presence of quill knobs in
> > Velociraptor is consistent with the idea, championed
> > by Gregory Paul and others, that dromaeosaurs were
> > secondarily flightless, as flightless birds are less
> > likely to possess quill knobs.
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