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RE: Why did small dinos become extinct?



Jim Cunningham wrote:

> Might quill knobs have evolved for carrying airloads generated for 
> directional control 
> (same thing as evolving for flight....) ?

Yep.  This would qualify as incipient flight behavior, wouldn't it?

James Aronis wrote:

> I was going to suggest an alternative theory for the presecnce of quill
> knobs and their supported structures in non-volant dinosaurs in the
> recent thread about this topic, but declined to do so. What if the quill
> knobs did not support 'feathers,' but derived structures to aid in prey
> capture?

Yes, I think that's an interesting idea.  The "derived structures" could 
actually be precursors (or at least homologs) of feathers.  Gishlick suggested 
that predators could have used their large forelimb feathers to herd prey 
(small or large) in their direction.  But I could be getting away from your 
idea....

Personally, I think quill knobs were present in _Velociraptor_ (and maybe 
_Rahonavis_ too) in order to reinforce the attachment of feathers to the arms, 
so they weren't plucked out during the hurly-burly of grappling with struggling 
prey.

Cheers

Tim


>
> James
>
> jrc wrote:
>>
>> ----- Original Message ----- From: "Tim Williams"
>> 
>> To: ; 
>> Sent: Thursday, December 13, 2007 6:12 PM
>> Subject: RE: Why did small dinos become extinct?
>>>
>> (2) quill knobs, which were once thought to have been indicative of
>> flight (or at least flight ancestry) are now reported for
>> _Velociraptor_, suggesting (but not proving) that this character may
>> not have originally evolved for flight. <
>>
>> Might quill knobs have evolved for carrying airloads generated for
>> directional control (same thing as evolving for flight....) ?
>> Jim
>>
>>

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