Re: MORE BASAL ORNITHISCHIAN STUFF

[Dinogeorge@aol.com]

In a message dated 98-09-15 22:18:55 EDT, Tetanurae writes:

<< GO<<Had pretty much the same kinds of cheek teeth.>>
 
 George, this is really not for certain.  All of the preserved teeth of
Pisanosaurus are worn, so their original un-worn shape isn't known.
Heterodontosaurid cheek teeth are only really distinctive in their un-worn
newly errupted form.  All we know for sure from the teeth is that it a) wasn't
an iguanodontian and b) wasn't a ceratopid, aside from that, the worn cheek
teeth don't help much.>>

Didn't say they were exactly like heterodontosaurid teeth. That would be too
easy. But they lack cingulum, are closely spaced, and are more or less chisel-
shaped--as in heterodontosaurids and unlike virtually all other ornithischian
teeth, except, interestingly, psittacosaur & protoceratopid teeth. Differ in
details, of course, as might be expected.
 
<< Again though, the primitive ankle and propubic pelvis, as well as the lack
of fangs and an arched diastema, demonstrate that Pisanosaurus probably is not
a heterodontosaurid, but instead the most basal ornithischian known. >>

Not at all convinced pelvis was propubic; could well be impression of prepubic
process. Need more material, naturally. Ankle and foot definitely primitive
and suggestive of not >fully< erect stance, as in some prosauropods.