Re: PISANOSAURUS

[jconrad@lib.drury.edu]

--On Tuesday, September 15, 1998, 4:13 PM +0000 Philidor11@aol.com wrote: 

> Just curious:  The Dinosaur Dictionary (Glut 1972, 1984 edition) says:
> Pisanosaurus-...This primitive ornithiscian is known only from fragmentary
> material found in Argentina, including limb bones, ribs, metatarsals and
> incomplete jaws.
> How was it classified as a plant eater and propubic?

As for propubic, there was a partial impression fo the pelvis (as reported
by Sereno, 1991).  The illustration supplied in this reference is relatively
convincing in that the pubis probably was oriented cranially.  Whether or
not this orientation was sloping forward or vertical is hard to say as the
pubic impression includes only the most proximal portion.  

As for heterodontosaurid characteristics and/or herbivory:

"Portions of the right mazilla and lower jaw are preserved and show the
presence of a well developed cheek emargination, a more advanced condition
than in _L[esothosaurus] diagnosticus_. . . The lateral surface of the
surangular and angular is depressed, reminiscent of the condition in
_Heterodontosaurus_. "  (Sereno, 1991: 174)

but:

"The [wear] facets [on the cheek teeth] . . . do not form a continous
occlusal surface as occurs in _Heterodontosaurus_. "  (Sereno, 1991:  174)

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Reference:

Sereno, P.C.  (1991).  "_Lesothosaurus_, "fabrosaurids," and the early
evolution of Ornithischia."  _Journal of Vertebrate Paleontology_ 11:2.  pp.
169-197.