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Re: PTEROSAURS WITH 5 MANUAL DIGITS



In a message dated 96-09-29 15:51:06 EDT, znc14@ttacs1.ttu.edu (Jonathan R.
Wagner) writes:

>         The idea was, why would pterosaurs lose it if George is
> maintaining that the only explanation for this serial digit loss is
> the structure of the avian wing.  It is a counter-example.  That's
> all.

I never said that serial digit loss can >only< be explained by the
incorporation of the forelimb into a feathered wing. I say that, given the
evolution of feathers and the attachment of feathers along the forearm up
through the second digit (which ornithologists call digit III, by the way),
and given the architecture of feathers and how they extend and unfurl
backward over the succeeding outer digits in modern birds, we can understand
why the outermost digits of the forelimb were lost. BADD theory provides no
such understanding.
 
> >With birds, things are different. Digits do not play a part in
> >support of the (avian) distal aerofoil, and retention of them could
> >not be advantageous.
> 
>        Once again, I hardly care.  The idea is that George is making
> mysteries where there are none.  He says that there is no
> explanation for the digit loss other than the feathered wing.

You're misrepresenting my views here. Tut, tut. Go back and read my preceding
comment.

>  I say that the feathered wing had to come about after the digit
> loss, because otherwise the wing would be based around another
> digit, as it is in pterosaurs. All the five-fingered pterosaur thing
> does is strengthen my point.

Which other digit, and why? BCF says nothing about >which< digit of the
forelimb would or should be chosen to bear feathers, since the ultimate
reason for that choice probably lies in the mutation that initiated the wing
in the first place.