OFF THE WALL IDEA

[Tetanurae <Tetanurae@aol.com>]

I have been ruminating on this for a few days now....   Having reviewd
Galton's 1973 description of the type (and only) skull of _Parksosaurus_ and a
few things really stuck out to me, most noticibly is that there are quite a
few features that are very similar to _Gaspirinisaura_.

I do not have Parks' original 1926 description of the skeleton, but should
within the next few weeks, so I can't really comment on postcranial
similarities at this time.  However, the similarities I have found in the
skulls are as follows:

1) Quadratojugal long and slender with a long thin ascending process and a
smaller ventral flange.  This differs from the quadratojugals in basal
ornithopods which are usually massive bridges from the jugal to the quadrate,
and the quadratojugals in more derived iguanodontians which are usually
extremely reduced and closely appressed to the quadrate.

2) Quadratojugal joins the jugal about 2/3 of the length of the shaft from the
articular surface (ie, the quadratojugal joins the shaft of the quadrate 1/3
of the shaft's length above the joint with the lower jaw.  In most basal
ornithopods the quadratojugal joins the jugal nearly at the articular surface
of the quadrate.  In later iguanodontians the jugal/quadratojugal joins the
quadrate up higher like in _Gaspirinisaura_ and _Parksosaurus_.

3) Jugal with a short caudal ramus.  In all dinosaurs, the jugal is a
triradiate bone plesiomorphically: a rostral ramus that joins with the maxilla
(and sometimes the lacrimal), a dorsal ramus that joins the postorbital, and a
caudal ramus that joins the quadratojugal.  In _Gaspirinisaura_ the caudal
ramus is all but gone, and in _Parksosaurus_ it is very small.

Unfortunately, both of these taxa are missing the very diagnostic premaxillae,
and I am completely unable to get ahold of a decent picture of _Parksosaurus'_
cheek teeth so they cannot be compared as yet with those of _Gaspirinisaura_.

So, what do you all out there think?  Am I completely crazy?

Peter Buchholz
Tetanurae@aol.com

Charlie, you do remember the story of the man who got everything he ever
wanted?
No, what happened?
He lived happily ever after.