Re: MORE BASAL ORNITHISCHIAN STUFF

[tlford@ix.netcom.com]

Tetanura
> 
> George Olshevsky wrote (quoting me):
> PB<<It was not a heterodontosaurid because it didn't have
>  the fangs, and also had none of the other specializations of
> heterodontosaurs.>>
> 
> 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.
> 
> 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 all heterodontosaurids have fangs (and don't say they weren't found,
some of them didn't have them).

Also, which may or may not help Pisanosaurus, fragmentary
heterodontosaurid skull matrial is known from a fragmentary skull. 

BAEZ, A. M., and C. A. Marsicano, 1998. A heterodontosaurian
ornithischian in the Upper Triassic of southern Patagonia? Journal of
African Earth Sciences, Volume 27, Number 1A: 14-15.

Tracy