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Re: pterosaur toes



Dan Bensen wrote:

<I notice that in many reconstructions of primitive
pterosaurs and the ansestors of pterosaurs (like the
prolactiforms), the outermost toe is shown bent under
the foot to sort of prop the appendage up. Is there
any particular reason for this arrangement?>

  It is a good suggestion for support, but is unlikely
to be proved anytime soon; the pes was capable of
support in fossils which were digitigrade; apparently
plantigrade pterosaur pes lack the elongated toe
(pterydactyloid synapomorphy). Fossils show the fifth
digit being flexed over the metatarsus in several
non-pterodactyloids, such as *Rhamphorhynchus* and
*Dimorphodon*, which suggests the toe was pulled by
the digitis tendon more strongly then the flexor
tendon. Not quite sure of the functional implications,
haven't made models to test this all, but the
braciopatagium would change shape significantly if the
toe were pulled over the foot. Whether this is a
taphonomic only condition I think is being studied by
someone(s), but can't be sure. Perhaps Dave Unwin or
Dave Peters can elaborate; I know the latter has
talked about it on his site.

=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.

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