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In a message dated 97-09-02 13:50:56 EDT, martz@holly.ColoState.EDU (Jeffrey
Martz) writes:

<< However, this is not the case with _Troodon_, or for
 that matter, _Aublysodon_.  The teeth are very unusual and derived, and in
 the absense of any other cranial material from different species with such
 teeth, diagnosing taxa with them is no more strange then assigning
 ceratopsian species based on fairly complete skull material, but lacking
 postcrania.  One could make the assertation that an isolated ceratopsian
 skull should not be lumped with a complete ceratopsian skeleton with a
 identical skull because later discoveries could reveal a species with
 identical skulls, but very different postcrania.  New discoveries can
 always change things, but _Troodon_ and _Aublysodon_ teeth are very
 unusual, and for the time being they seem to be diagnostic. >>

Alas, _Aublysodon_ teeth are no longer diagnostic. There's little doubt in my
mind (at any rate) that such teeth (unserrated carinae, D-shaped
cross-section) are characteristic of a whole subfamily of tyrannosaurids.
Certainly _Stygivenator_ and the unnamed Oklahoma "Aublysodon" represent
different genera, but each has the characteristic _Aublysodon_ premaxillary
teeth, as far as we know. _Alectrosaurus_ also has _Aublysodon_-like
premaxillary teeth. _Aublysodon_-like teeth, of several different size
grades, occur in many Late Cretaceous strata in western North America and
eastern Asia; it is no longer conceivable that a single dinosaur genus is
responsible for all these occurrences.