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Re: Do we have dromaeosaurid evolution backward?

On Aug 25, 2011, at 10:41 PM, Tim Williams wrote:

> Although the "proto-wings" of bird ancestors might well have been
> quite similar to the incipient wings of modern bird chicks that use
> wing-assisted-incline-running (WAIR), the wing movements required for
> WAIR are actually quite sophisticated.  There are doubts over whether
> the primordial flight apparatus of bird ancestors was up to the task
> of performing WAIR.  Whereas the feathers of basal paravians are quite
> advanced by avian standards, the skeletal (and by inference, muscular)
> adaptations of these basal paravians were comparatively poorly
> developed.

Precisely.  It is particularly the upstroke phase that is in question in this 
regard.  The upstroke phase has received considerably less attention in the 
paleontological and flight evolution literature than downstroke mechanics.  I 
suspect this comes from a fundamental interest in power generation combined 
with a lack of consideration of how vorticity is generated and ended on 
flapping wings.



Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
(443) 280-0181