Re: dinos and birds

["James R. Cunningham" <jrccea@bellsouth.net>]

Jaime A. Headden wrote:

> Stephen Moore (smooreph@yahoo.com) wrote:
>
>   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.

I would say 'some' rather than 'most', and would say 'probably was' rather than 
'was'.  I have no idea about percentages, but would suspect an advantage to 
decoupling in the larger animals to make launch easier.  To me (based on the
actinofibril layout along the r/u and the humerus), the Zittel wing does not 
seem to be capable of an ankle attachment, and probably not a knee attachment 
-- but I do think it would be capable of an upper thigh attachment somewhat 
like that
of P kochi.

> 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.

I agree.  I find the purported ankle-attached azhdarchid to be unconvincing -- 
but can't make a final personal decision till after I see it in person.

> 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.

Again, I agree -- I wouldn't bet that there are no flightless pterosaurs.