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Heterodontosaurs



In a message dated 97-09-04 21:37:30 EDT, Tetanurae@aol.com writes:

<< PB:I agree with George that Heterodontosaurids (including _Echinodon_) are
 probably not ornithopods, but instead basal marginocephalians by way of the
 large jugal horns (which are quite different from those on zephyrosaurs),
 three fang premax teeth and some other characters of their vertebral column
 and pelvis.  Oddly enough, almost every single person who has ever worked on
 Heterodontosaurs up close and personal insists that they are in no way shape
 or form ornithopods, but somehow related to ceratopians or pachycephalosaurs
 or both. >>

In my article for Gakken back in 1993, I used the name Heterodontosauria to
denote the clade comprising heterodontosaurids and pachycephalosaurs. I noted
the jugal boss, the three fanglike premax teeth, and presence of a dentary
fang (lost in advanced pachycephalosaurs) with matching premax-max diastema
in the upper jaw amng the cranial characters uniting these groups.

_Majungatholus_ claded perfectly in between flat headed and domed
pachycephalosaurs, giving the impression that the frontals of pachys
thickened first in their phylogeny, followed by the parietals. Too bad it's a
theropod.