Re: Where to put *Scleromochlus*?

["David Marjanovic" <david.marjanovic@gmx.at>]

> > Now that pterosaurs have been moved away, *Scleromochlus taylori* finds
> > itself in Dinosauromorpha... but where exactly? Suggestions?
>
> It would be the most basal form, if it is a member.  Scleromochlus lacks
[...]

Thanks a lot!

> Remember though, Scleromochlus has
> several characters in common with pterosaurs.

What I can find as supposed synapomorphies of Pterosauromorpha (includes
Pterosauria, *Sharovipteryx* and *Scleromochlus*):
- skull at least as large as ribcage (not exactly immune to convergence)
- longer forearms than upper arms (more convincing, but e. g. paralleled in
birds)
- longer humeri than scapulae (basically makes "long arms" with the former)
- strongly reduced fibulae (compared to what?)
- metatarsals I through IV closely bunched together (as "opposed" to II
through IV closely bunched and I reduced, so the term "bunched" is
inapplicable, the condition in *Lagerpeton* + Dinosauriformes)
- and hook-shaped metatarsals V (plesiomorphy).
More characters exist, but I don't have

Philip J. Currie & Kevin Padian (eds.): The Encyclopedia of Dinosaurs,
Academic Press 1997

here (where I've found the characters I just explained). These must be more
detailed features, such as presences and absences of trochanters and stuff.

> Assuming pterosaurs are not
> archosaurs, could Scleromochlus be close to Cosesaurus, Sharovipteryx and
> such?  Any thoughts from Dave Peters?

IMHO unlikely, because of the following unscientific arguments =8-] :

- it looks quite a lot like *Marasuchus* in general shape (though the
skeletal reconstructions I know might be reconstructed after *Marasuchus*, I
don't even really know how much is known of *Scleromochlus*);
- it looks a lot different from *Sharovipteryx* (see
http://www.pterosaurs.net/Sharovipteryx.html, though less so from
*Cosesaurus* http://www.pterosaurs.net/Cosesaurus.html)
- David Peters seems to disagree
(http://www.pterosaurs.net/Pterosaur_Origins.html, also look at the long
character lists).

Well, that's my 7th e-mail today, and it's nearly midnight. So I'll go to
bed, dizzy from learning that the *Spinosaurus* holotype isn't adult and
estimated maximum sizes are... :-o
nbh j [<-- head banging on keyboard]