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Re: TROODON, FABROSAURUS AND TOOTH TAXA IN GENERAL



George, you constatntly refer to your articles written for Gakken.  As far
as I know these are all published in japanese only and available only in
the defunt Dino-Frontling magazine, yet you cite them as though everyone is
supposed to have read them or at least as though we are suppsed to be able
to refer to them if we want to see what you said.  Why?

----------
> From: Dinogeorge@aol.com
> To: smithjb@sas.upenn.edu; dinosaur@usc.edu
> Subject: Re: TROODON, FABROSAURUS AND TOOTH TAXA IN GENERAL 
> Date: Tuesday, September 09, 1997 10:24 AM
> 
> In a message dated 97-09-09 08:30:17 EDT, smithjb@sas.upenn.edu (Joshua
> Smith) writes:
> 
> <<    _Aublysodon_ teeth are not diagnostic?  Really?  OK, so where is 
>  this published?  A), is there enough data for this hypothesis to be 
>  considered valid and testable, and B), by which method have you tested
it?>>
> 
> I published this notion in my articles on tyrannosaurid relationships for
> Gakken. _Aublysodon_ teeth have been found in several different genera,
so
> they are not diagnostic to the generic level. >This< test is finished.
They
> are, however, (presumably) diagnostic of the subfamily Shanshanosaurinae,
the
> only subfamily in which they've so far been found. Showing something is
> nondiagnostic is akin to falsifying a hypothesis, which can be done with
a
> single counterexample; showing something is diagnostic is akin to proving
a
> hypothesis true, which cannot be done except perhaps by the test of time.
> Tomorrow someone may find _Aublysodon_-like teeth in genuine
tyrannosaurines,
> and "poof!" there goes the diagnostic value of those teeth at the
subfamily
> level.
>  
> <<    As far as your (George) hypothesis (I assume that you have 
>  analized this enough to determine that it IS a testable hypothesis...) 
>  concerning the lack of denticles on what you are calling lateral carinae

>  on the premaxillary teeth of _Aublysodon_, where do my cf. _Aublysodon_ 
>  premaxillary teeth with denticulate carinae fit into this scheme.  How 
>  many specimens have you used in your test of your hypothesis?>>
> 
> I've gone by the literature: about 20-30 references on _Aublysodon_.
> _Aublysodon_-like premaxillary teeth _with_ denticles may belong to
juvenile
> tyrannosaurines. If you can show that denticles can exist on
shanshanosaurine
> premaxillary teeth, it would be a most valuable finding for the taxonomy
of
> tyrannosaurids. By increasing the number of genera in Tyrannosauridae
that
> may have _Aublysodon_-like teeth, you'll absolutely destroy that genus.
>  
> <<    Also, just to play Devil's Advocate, I would say to both Jeff and 
>  George, just exactly what are you calling "diagnostic" about any of
these 
>  teeth and has this hypothesis been tested and by what method?  
>  _Aublysodon_ sp. teeth are unusual, yes, but just what is diagnostic 
>  about them?  Position and possession/lack/shape of denticles?  Is this 
>  diagnostic for theropod dentition?  Can you prove it?  Before we can say

>  that teeth are not diagnostic or are diagnostic, work needs to be done 
>  on what is or isn't diagnostic about them and why.  This is a rather 
>  large project that has not been done yet for any dinosaur taxon.>>
> 
> I see you've gotten to the extreme end of the arc of the swinging
pendulum
> concerning what is or is not diagnostic with respect to dinosaur taxa.
See
> above.
>   
> <<    As for you point about it being inconceivable for a single 
>  dinosaurian genus to produce such an abundance of teeth across such a 
>  large paleogeographic (indeed geographic) area, why not (this is NOT to 
>  say that I agree or dissagree with you, I am just saying that you have 
>  dropped a rather large speculation out here, and do you have any
evidence 
>  to back up the claim)?>>
> 
> I know of no bona fide dinosaur genus that is found with such a wide
range
> and duration. (Entire Campanian and Maastrichtian; eastern Asia as well
as
> most of western North America.) In previous instances of such wide
> paleobiogeographic ranges, such as with _Megalosaurus_, systematic
revision
> has subsequently shown the genera to be polytypic: several genera lumped
into
> one. Since _Aublysodon_ is based >entirely< on premaxillary teeth, it is
> overwhelmingly likely that this has happened in this case.
>  
> <<    This falls very close to the nasty border of discussing exactly 
>  what is a dinosaurian genus in the first place; something that would be 
>  very interesting, but probably also very frustrating to discuss in this 
>  forum.>>
> 
> Since dinosaur taxonomy above the level of individual specimens is
entirely
> subjective (cladistics notwithstanding: Nature doesn't care what we call
> these things or how we arrive at our classifications), this would indeed
be a
> fruitless discussion. Like the perpetual argument between lumpers and
> splitters.