Re: "Flight theory has legs"

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

Graydon (oak@uniserve.com) wrote:
 
<This can't be extended to aviform dinosaurs, though; they don't have the
basic mammal tree-or-ground-hugging-splat posture.>

  Typical scanorial locomotion is not limited to trunk-hugging, but
extends to branch-walking, canopy-leaping, and so forth. Non-sprawling
arboreal/scansorial animals include the chameleontid lizards. The
non-sprawling posture, however, does not neccesarily limit the effect of
the manual AND the pedal claws on the same substrate. A semi-sprawling,
semi-hugging posture is possible, as first restored by Chatterjee, for a
spread-armed, tucked-legged position. I restore this to some degree on the
Dinosauricon, for elucidation (near the bottom of my gallery page).
Another version, featuring a vertical featherless *Deinonychus*, is also
available apart from *Sinornithosaurus* (but the arm position is
outdated). 

<Until someone finds quadrepedal bird tracks, I think the
no-substrate-contact is a pefectly decent assumption.>

  No one is suggesting birds could be quadrupedal -- or extant birds, in
any case (I made a clear distinction in my prior post). Yet. I think

<I am also unable to come up with a hand-claw climbing scheme that
wouldn't involve the feet at all; the shoulder anatomy wouldn't let them
hang straight down from the hands.>

  Well, if orangutans can, who knows. However, I don't think anyone
suggested that they could. Alos, if a bird hung upside down, belly up, the
arm position is not impossible for this, given claws.

  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.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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