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Re: solnhofen





 

----- Original Message -----
From: Dinogeorge@aol.com
Sent: Tuesday, May 01, 2001 7:56 PM
To: dinosaur@usc.edu
Cc: Dinogeorge@aol.com
Subject: Re: solnhofen

In a message dated 5/1/01 1:18:58 PM EST, graydon@dsl.ca writes:

<< 1) whenever the first bird evolved, the wing stroke had to be
initially exapted from something; if that *isn't* a predatory grasping
stroke, what was it?>>

A simpler wing stroke. A climbing movement. A fluttering movement. Take your
pick; the fossil record is too poor to constrain even wild guesses. But the
articulation of a dromaeosaurid arm and hand prohibits a >grasping< stroke.

<< 2) what part of a full, four phase wing beat *can* be co-opted as a
grasping predatory stroke?  The adaptations for flight more or less
force full extension of wings when used at or near full power; geese,
frex, do threat displays without fully extending their wings but when
they're trying to hit you with them have to fully extend them to
generate any power. >>

Birds can fend off a predator by slamming it with their wings. Now imagine
that the wing still has a set of two or three claws; >this< is where the
dromaeosaurid/maniraptoran forelimb comes from.

      >The wing stroke of modern
birds is pretty much useless for anything else, so when a modern bird opts
for secondary flightlessness, the wings usually vestigialize without function
in its descendants.<:

   *Titanis* (a large Phorusraschid) in early Pleistocene North America had highly derived wings with re-developed claws and large muscle attachment areas. 




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