[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Diphyletic pterodacs et al.

Dr. Padian's recent comments regarding my questioning the monophyly of
pterosaurs and the inclusion of same within Ornithodira included the

<<a methodological question here that ought to be of central importance to
readers of this list. One of the tenets of phylogenetic systematics is that
you can't assert convergence, you have to demonstrate it by showing that
another phylogeny is better supported.  And that means a full cladistic
analysis with all the characters. >>

How 'bout if I shoot down the currently accepted dogma with a point by point
rebuttal and then offer a reason why pterosaurs are fundamentally different
(see below) and then offer a list of characters that tie pterosaurs more
closely to protorosaurs?  That's not a cladistic analysis is it?  I'm sorry,
I've reached the limit of my credentials and brain cells.  I don't do windows
and I don't do cladistic analysis.  I wouldn't know how.  I'm an art
director, I'm in the idea business.  I thought the emperor had no clothes and
I spoke up about it.

I must have sent out at least a dozen copies of an unpublished manuscript
questioning the inclusion of pterosaurs within the group known as
ornithodira, including copies to Drs. Gauthier, Padian and Sereno and the
Dino Forum.  I've received replies only from Dr. Padian (whose reply mirrored
the recent posting) and Dr. Rupert Wild (who suggested I publish it). In
short the manuscript points out that nearly every ornithodire feature either
cannot be found in pterosaurs, is too difficult to determine from the scrappy
remains of pterosaurs, or may be convergent with pterosaurs.  The
convergences all spring from this bipedal issue.  

I have demonstrated that pterosaurs and other diapsids, including dinosaurs,
had fundamentally different methods of moving the femur.  This feature
appeared long before wings did.  Pterosaurs lack or have greatly reduced
caudofemoralis muscles as evidenced by greatly reduced transverse processes
and hemal arches on the caudals, thus they do not retract their legs in the
manner of other diapsids.  By default, they rotate them.  This makes little
external difference in pterosaurs with a femoral head/shaft angle of 120
degrees of so, as in the case of Dr. Padian's _Dimorphodon_.  It makes a
great deal of difference in those pterodactyloids in which the femoral
head/shaft angle closes in on 180 degrees.  This issue is going to stay open
and I think we'll be hearing more about it in the near future as discoveries
in Italy seem to portend.

I am going to back off a bit on the pterodactyloid monophyly issue, but
reserve the right to charge at it again.  A bit more research as revealed
that the important characters are not well-known enough in a sufficient
number of genera.  I saw a trend, but that doesn't prove anything.  

By the way guys, it was a posting, not a poster session.  I thought this was
a forum for serious cocktail chatter.  I was looking to be falsified by
exceptions to the trend I spotted, but thanks for reminding me that a full
cladistic analysis was necessary.