re: dinos and birds

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

Stephen Moore (smooreph@yahoo.com) wrote:

<Since now the consensus is that the pterosaurs were furry, warm blooded,
highly active and robust animals (contrary to opinions when I was a child
of the fragile pterosaurs, barely able to glide from tree to tree) why did
they not survive like the birds? 
  GSP 2002 speaks of several advantages birds have over the other flying
vertebrates mainly in the that the primary flight structures of birds, the
wings, are independent of the walking/running appendages, the legs, unlike
bats and probably pterosaurs who have them joined.>

  Seemingly on the contrary, some researchers, including Jim Cunningham,
have posited that a narrow-wing design with an uncoupled forelimb from
hindlimb, was present in most pterosaurs. Some pterosaurs show a coupled
wing-leg system, as in *Sordes* or maybe *Rhamphorhynchus,* but no late
Early or any Late Cretaceous large pterosaur, or any pterosaur with a wing
length greater than 3ft, is known with sufficient integument to determine
the possible condition of coupled versus decoupled fore- and hindlimbs.

<Evolution has developed bats and pterosaurs into excellent flyer's but
they would be hard pressed to evolve further into terrestrial bipeds or
quadrupeds. Birds could theoretically fly to an island, colonize, fill
niches, grow gigantic and flightless and prosper for a few million but
when the water levels begin to rise, for whatever geological reason, the
bird cannot return to the air and perishes.>

  While the use of inferring the small bats to the fantastically huge
pterosaurs with coupled limbs would seem to be intuitively linked, the
actual connection would seem to have so-far escaped those who have looked
at this problem, as to my knowledge, no one has yet to "determine" for the
satisfaction of scientific interest, why pterosaurs should NOT have become
flightless, whereas birds were able to do so in the Late Cretaceous
(hesperornithids/baptornithids) -- there are no flightless bats. Part of
the problem seems to be stuck in equating bats and pterosaurs as
essentially the same thing, but no one has yet to determine why a membrane
that extends between fore- and hindlimbs would prevent loss of flight,
when pterosaurs seem perfectly capable -- moreso in fact than bats -- to
walk around as fly.

  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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