Re: Pterosaur membrane fibres

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

Hi Martin,
Your description of the skate fibers is most interesting.  Do the skate
fibers align with the principal stress axis?  In the outer wing, that would
be generally spanwise, diagonalling slightly aftward as they go outboard.
In pterosaurs, the outer wing principal stress axis (which is quite similar
to that in a Marconi rigged sail) parallels the aktinofibrils and far
exceeds the secondary stress axis (in other words, the pterosaur wing is not
far removed from a wrinkling condition, even in flight).  I don't think
anyone can really answer your question at this point.  I'd suggest
contacting Alex Kellner, who has some fairly well preserved aktinofibrils.
May I forward your e-mail to Dr. Peter Jackson and Mike Johnston at the
University of Auckland?  Your comments are pertinent to Johnston's Ph.D.
thesis about the flexible membrane wing of Pteranodon.  Is it possible that
your semi-articulated fingers are intercalations?
Best wishes,
Jim Cunningham

Martin Human wrote:

> Hi,
>
> I noticed that the "wings" of the skate (or ray, I only
> have a cook book to guide me as to identification) contain long,
> semi-articulated "fingers" of cartilagenous material. Are these a
> suitable analogy for the membrane fibres of certain pterosaurs