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Re: Echinodon

In a message dated 97-09-05 12:34:00 EDT, th81@umail.umd.edu writes:

<< Sereno (1997, Annual Rev. Earth & Planetary Sci.) refers _Echinodon_ to
 Heterodontosauridae.  He also mentions a very small Early Jurassic
 heterodontosaurid from the western U.S. (maybe Kayenta Fm.? he doesn't say)
 in the collections of the Musuem of Comparative Zoology, Harvard U. >>

I classified _Echinodon_ as a basal heterodontosaurian in my Gakken article
way back in 1993 or so. But it has a different pattern of premaxillary and
dentary fangs, so it should lie outside Heterodontosauridae +
Marginocephalia. Same holds for the small Fruita "Echinodon" (it's gotta be a
new genus) whose jaw is illustrated (thanks to Dinamation's George Callison,
who presently has the specimen) in that article.

The notion that heterodontosaurids might be basal marginocephalians goes back
at least to Zhao's 1983 paper in _Acta Pal. Polonica_--the one wherein he
introduces all kinds of nomina nuda. That part made a great deal of sense to
me when I read it.