Re: Broader than Dinosauria [Additional Info]

[AM Yates <Adam.Yates@bristol.ac.uk>]

On Mon, 10 Sep 2001, Jaime A. Headden wrote:

>   Mickey has the *Saturnalia* paper, and indicates the text says that
> the pelvis has a partially open acetabulum: I lack details, and the
> only pelvic figures are part of a reconstruction. I need to see the
> pelvis before I can comment. 
> 

I have seen the pelvis of Saturnalia. The state of the acetabulum is
much like Guiabasaurus. The medial wall of the ilium is virtually
complete and has a horizontal ventral margin in lateral view (not even a
tiny bit concave).  The opening in the acetabulum is formed by the
retraction of the medial walls of the pubis and Ischium, as in
Guiabasaurus. I am fairly sure that this is the true basal state of the
dinosauria and it is fair to describe this condition as partially open. 
Ventrally open might be a better term.  It is worth noting that the
ilium of Lesothosaurus is also very similar with a large medial wall and
an almost straight ventral margin - based on personal observation of
BMNH material). Thecodontosaurus is somewhat intermediate with a large
medial acetabular wall but a gently concave ventral margin. 

cheers

Adam Yates