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RE: Origin of bird flight: ontogenetic-transitional wing (OTW) hypothesis




Michael Habib wrote:


> That makes sense to me, as well, but I'm not sure it is enough for WAIR type 
> behaviors, even if it was enough for generating some aerodynamic forces. 
> The issue is that the authors tacitly assume that juvenile galliform birds 
> are "near-volant" in the same way that dromeosaurids et al. would have been, 
> and 
> I am not yet convinced that this is the case. The problem is that WAIR 
> behavior might actually require a more derived shoulder architecture and 
> power 
> supply (i.e. pec minor with trioseal canal) to work, because the upstroke 
> probably has to be rapid.


Yes, that's an excellent point.  At what stage in theropod phylogeny was the 
pectoral architecture (both muscular and skeletal) capable of sustaining 
forelimb excursions with enough power to generate WAIR?  Would a pre-WAIR 
incipient wingstroke serve any aerodynamic benefit at all, such as improving 
traction and/or helping the biped run over uneven terrain?  I don't know the 
answer to any of these questions, and (more to the point) I don't know how 
you'd go about finding an answer for non-avian (or non-ornithothoracean) 
theropods.



Cheers


Tim
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