-----Original Message-----
From:
David Marjanovic <david.marjanovic@gmx.at>
To:
The Dinosaur Mailing List <dinosaur@usc.edu>
Date:
Wednesday, September 27, 2000 2:58 PM
Subject: Pterosaur
relationships
Maybe this topic should not be discussed on
this list, but the current view of Ornithodira has become so entrenched that
e. g. The Dinosauricon includes pterosaurs. My question is: What are, to
date, the arguments for pterosaurs being close relatives of dinosaurs rather
than Prolacertiformes?
A website providing the evidence for
(Prolacertiformes + (Langobardisaurus + (Cosesaurus +
(Sharovipteryx + Pterosauria)))) is http://home.stlnet.com/~azero/Pterosaur_homepage.
The evidence presented there is quite compelling, but the
usual hypothesis makes some sense (e. g. one origin for ?bipedalism,
??digitigrady and endothermy), so I'd like to know whether we really have to
abandon it.
Padian gives an interesting synopsis of the features
relating pterosaurs to dinosaurs, (as well as possible links to lagosuchians
and scleromochlus) in his article titled:"The Origin of
Pterosaurs" (1984) Third Symposium on Mesozoic Terrestrial
Ecosystems" Wherin he states..."Like dinosaurs,pterosaurs have
unusually large skull openings. The presacral vertebral column is
regionalized into three distinct segments(cervical, cervico-thoracic, and
lumbar: see Bonepart 1975). The scapular is long, straplike, and not
distally flared; the coracoin is longer than wide. There are at least three
sacral vertebrae, and possibly four. The femur has a "fully
off-set head"(Charig 1972)........" yada yada yada(although a
short, and interesting paper, can`t copy it all here!)
For an even more detailed analysis of synapomorphies
linking ornithodirans check out Sereno`s papers : "Dinosaurian
Precursors from The Middle Triassic of Argentina:Lagerpeton
Chanerensis" Sereno and Arcucci JVP 13 (4):385-399, Dec
1993
and "Dinosaurian Precursors from The Middle Triassic
of Argentina:Marasuchus Lilloensis,Gen. Nov." Sereno and Arcucci JVP 14
(1): 53-73, Mar 1994.
I don`t know if any of these authors believes in one
origin for "bipedalism, digitigrady, or endothermy', but personally, I
favor a non-convergent view of these traits........and, for a possible
alternate view (strictly my own ...it seems...8^) of phylogeny that might
link prolacertiforms to pterosaurs, as well as birds and dinosaurs, check
out my website at: http://www.capital.net/~larryf/