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Re: The "ideal" Eumaniraptoran arm motion



-----Original Message-----
From: Pharris Nicholas J <pharrinj@plu.edu>
To: Larry Febo <larryf@capital.net>
Cc: Jeffrey Martz <jeffmartz@earthlink.net>; dinosaur@usc.edu
<dinosaur@usc.edu>
Date: Tuesday, March 02, 1999 4:40 PM
Subject: Re: The "ideal" Eumaniraptoran arm motion




<Bear in mind that the drag produced by hauling wings or slabs of cardboard
through the air is greatly determined by the angle at which you do it.  If
you hold the cardboard/feathers vertically, it is very difficult, but if
you slide the wing through the air horizontally (which, because of the
semilunate carpal block, is the plane in which maniraptoriform arms were
made to operate), it is not that hard.>


Gee,...wish I could draw a diagram. There seems to be some
confusion...(maybe mine).OK, lets say the vertebral column is a straight
axis (for the sake of simplification).And the wing motion, when this axis is
parallel to the ground (as in a bird in flight) causes most drag with the
downstroke (towards the earths surface).

Now, in a Theropod bolt upright (an exaggeration), with the same arm motion,
and feather alignment, chasing prey, the drag would be caused with the
feathered arms being brought together in the direction of the prey ( also
the direction of travel).

Therefore, there would be significant drag that would oppose the forward
motion of a theropod chasing down prey....at least at the final moment
(assuming its arms were tucked) when it reaches out to grab the prey.

More likely, the theropod was leaning somewhat in the forward direction with
axis at what?...about 45 degrees?  Still there would be significant amount
of drag.