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



It might also be worth mentioning that the fast upstroke can be a mechanism for increasing the power output of the upstroke muscles relative to the downstroke muscles (due to the increased contraction speed of the upstroke muscles). Like Mike, I have some reservations about whether this was readily available to early birds because of their shoulder geometry.
JimC


----- Original Message ----- From: "MICHAEL HABIB" <habib@jhmi.edu>
To: <dinosaur@usc.edu>
Sent: Thursday, January 24, 2008 12:41 AM
Subject: Re: Origin of bird flight: ontogenetic-transitional wing (OTW) hypothesis



Considering that basal birds had a deltoideus-driven upstroke, and possibly less humeral elevation than modern taxa, it may be that the incline-running type mechanics were unavailable to them.

Cheers,

--Mike H.