Re: Wings and Such

[Flyinggoat@aol.com]

>About pterosaur hands....  I have been wondering this for a while.  >Is the
wing finger really digit four?  If it is, that would seem to >me a very
aquard way of evolving.  Think about it.  On a five >fingered animal (such as
yourself), why would digit four (your >ring finger) become the elongate
leading edge of a wing >membrane?  Why not digit five; the one closest to the
wing? 

   Not having studied the specific morphology of this, I have an idea about
it which may or not be close. 

HYPOTHETICAL CASE:                (once apon a time in the Permian)
The creature that became Pterasaurs' ancestor had the wierd 5 fingered hands
like the crocodiles and thecodonts.  Pre-pter became arboreal (or at least an
active climber) devoloping longer, more gracile fingers than before (just
like dear old Sapiens' ancestor), and at some point developed a
wing-membrane-like flap of skin off of it's hands. (I can see modern Howler
monkeys, Gibbons, or Siamangs using this as a boost in tree-leaping, but
something like this may have happened with the primate-relative bats,
anyways).  The wingflap was small intitially, but as it grew in size, the
hand started to move it's positioning to support it better (for better
control of the flap and less plummeting out of trees).  The pinkie just
wasn't strong enough to support the weight and stress of the membrane, so
Pre-pter lost it (removed it or fused it to the ring-finger to strengthen
it).  Thus being well on the way to developing wings.  THE END

   HOWEVER having had really advanced dinosaurs like Deinonychus having the
ring-toe developing a slashing blade and leave the pinkie toe to shrivel up
to a dew-claw positition (though remaining more flexible than the dog ever
could), or having T Rex loose the 3 fingers somewhere in it's ancestry, why
is it so odd that the ring-finger became a wingstrut?  Evolution does wierd
things.
   On an aside, which fingers are left on T Rex?  He's got 2 on each hand,
but which 2?  Are they fused carpals/phalanges, or lost carpals/phalanges?

Betty Cunningham(Flyinggoat@aol.com)