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FW: The ground-nowhere hypothesis on the origin of bird flight



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Tim.
=20
Just a thought here. The ground scenario of raptors using their
wings to balance themselves upright upon their prey most likely
was exapted after they no longer could grasp with their forelimbs.
=20
So what transpired in theropods to do this? That scenario may well
have started from the trees down with the proavis jumping upon
its prey leopard style. Next. How do you remove the forelimb action
from the hindlimb action in this style of predation? By developing=20
a sickle claw to grasp prey items thereby freeing the forelimbs to
hone the balancing act and exentually allowing the theropod to hit
prey over ever increasing distance from the origin of attack. This
also allows the theropod to swing up into a nearby tree if it misses
its target. Thereby positioning the animal for a quick renewed attack.
=20
Now. Show me my money!!! --dale=20


----------------------------------------
> Date: Fri=2C 9 Oct 2009 22:54:25 -0700
> From: tijawi@yahoo.com
> To: dinosaur@usc.edu
> CC: tijawi@yahoo.com
> Subject: Re: FW: The ground-nowhere hypothesis on the origin of bird flig=
ht
>
> dale mcinnes=20
>
>> A proavian can not be working both against/for gravity at
>> the same time? Why not use the wings as spoilers to pin
>> yourself against the substrate while running up a tree thereby
>> defying gravity?
>
>
> Yep=2C excellent point. This is the basis of WAIR=2C by which excursions =
of the wings supply improved hindlimb traction=2C allowing birds to run up =
inclined and even vertical surfaces. However=2C when applying WAIR to pro-a=
vians as part of the evolution of flight behavior=2C at what evolutionary s=
tage does the pro-avian become airborne - and for what reason? It's this sh=
ift to aerial locomotion where we need to look at the role of gravity - and=
 whether the pro-avian is using gravity to its advantage=2C or working agai=
nst it.
>
>
>
> Cheers
>
> Tim
>
>
>                                         =0A=
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