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Re: Marsupial flight (ex forelimbs)



--- "T. Michael Keesey" <keesey@gmail.com> wrote:
 
> Incidentally, it kind of seems that marsupial
> pouches would be
> *better* for a flying guild than placentalian
> clinging. And there are
> several lineages of gliding marsupials--it does seem
> odd that none of
> them have developed flight. (Although, given the
> rarity of amniote
> flight, especially amniote flight derived from
> skin-gliding, maybe
> luck has something to do with it.)
> 

Most marsupial pouches are toward the rear of the
female, probably to make the crawl from vagina to
pouch shorter.  As the young enter the pouch and grow,
the center of gravity would shift to the rear while
the center of lift would remain roughly at the wing
attachment (shoulders in placentals and birds).  This
creates an unstable condition which would either
hinder/prevent flight or require that the body be held
vertical as do some dragons in the movies.

Most placental mammal young that I've seen cling to
the chest - where the milk is.  This would keep the
center of gravity close to the center of lift if the
mother flew with a baby clinging.

I suspect that c.g.-c.l. relationships would be less
critical in short, relatively non-maneuvering glides. 
Most of the gliders I've seen on TV tend to land with
their bodies inclined toward vertical, so a pouch with
young might be advantageous. 

Glen Ledingham