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Re: TROODON, FABROSAURUS AND TOOTH TAXA IN GENERAL



> George brings up a point that I have been thinking about quite a bit
> recently.  Are tooth taxa really, truely diagnostic?  This runs a very fine
> line, and the conclusion I have come to is a very cautious no.

> Is this the right thing to do?  No.  Although the teeth associated with the
> skeleton named _Stenonychosaurus inequalis_ are similar to those of both
> _Troodon formosus_ and _Pectinodon bakkeri_, we cannot be 100% that they come
> from the same animal.  In fact it is quite possible, even probable that there
> was more than one animal running around North America with the _Troodon_
> tooth-type.

     Possible, but what makes you say "probable?"  Teeth are no
different then any other part of the skeleton; some are diagnostic for a
particular group, some are not.  Yes, perhaps one day a "_Troodon_" tooth
will be found in situ in a theropod jaw belonging to an animal other then
_Troodon_.  However, this could be true of ANY diagnostic skeletal element
for any dinosaur.  Some tooth types, and many other skeletal element (ribs
for example) are  known from more somplete skeletons to be fairly uniform
and un-diagnostic.  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.  Also keep in
mind that Phil Currie knows Judithian theropods, particularly thier teeth,
better then about anyone (having examined hundreds), and he considers them
valid taxa. His opinions should not be discarded so lightly.         

LN Jeff
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