RE: Powered Flight Definition (part of RE: Cost in Aquatic Birds (long))

["Jaime A. Headden" <qilongia@yahoo.com>]

Tim Williams (TiJaWi@agron.iastate.edu) wrote:

<I'm not familiar with Brian Cooley's model - could you elaborate?.>

  Brian's modle is available both on the National Geographic website,
under the dinosaur section, and in the famous 1998 dinosaur issue. It
shows what are at first fairly primate-like avian limbs and short
protofeathers on the trailing edge, which are bizarrely reminiscent of
sifakas.

<IMHO, the flaw in this theory is that the hands of eumaniraptorans
(deinonychosaurs and basal birds alike) seem unsuitable for grabbing onto
branches.>

  I don't see this as a problem. One simply turns the animal 90 degrees
and have it run along the branch. The arms serve as stabilizers.
Trunk-landing and bush landing need never involve so much as a grasping
hold, but a spread of the arms into the brush.

<But this would place enormous stress on the manus, especially if the
hands were used in a brachiation-like fashion to support the body.  In
other words, I just can't imagine small theropods swinging primate-like
through the canopy.  They don't have the forelimb architecture to pull it
off.>

  Indeed they don't. I do not suggest brachiation at all, but more of a
"flying-squirrel" analogy, something plausible at least for the smaller
animals like *Microraptor*, rather than the ~15lb *Sinornithosaurus*,
which may have been more of an understorey predator.

  Cheers,


=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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