RE: tiny-armed theropods

[Anthony Docimo <keenir@hotmail.com>]

> Date: Sun, 16 Oct 2011 14:11:38 +1100
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: tiny-armed theropods
> 
> Anthony Docimo <keenir@hotmail.com> wrote:
> 
> 
> > Let me make sure I understand this: the type tooth _Troodon formosus_ is 
> > not the same as other known Troodon teeth (while being a
> > likely member of the Troodont group)...
> > ...yet despite its differentness, we shouldn't call it distinct? Or we 
> > shouldn't pay it any attention?
> 
> 
> Not exactly.
> 
> 
> The genus _Troodon_ is based on a single tooth. If it turns out that
> the tooth morphology of _Troodon_ is shared by two or more troodontid
> species, then this morphology can no longer be considered unique (and
> therefore diagnostic) for _Troodon_. In this situation, _Troodon_
> would have to be considered a nomen dubium.
 
 It would seem to me that, if the _Troodon_ tooth morphology matches two or 
more troodontid genera (I assume you meant genera), then you'd know which 
troodontid clade _Troodon_ belongs to (which, granted, it was probably already 
grouped in).
 
 Is it possible for multiple genera to have identical teeth?  Even if they're 
99% similar, surely that remaining 01% could be used to determine the closest 
relatives of the _Troodon_ type fossil tooth.
 
 
> My example of _Deinodon_ is to show what *could* happen to _Troodon_
 
ah, okay.

> (it hasn't yet). _Deinodon_ was originally named from teeth that were
> once considered distinctive. However, later discoveries of
> tyrannosaurid specimens showed that the tooth morphology of _Deinodon_
> was actually common to several tyrannosaurid genera. So the
> _Deinodon_ teeth were therefore no longer distinctive (= diagnostic)
> at the genus or species level.
 
 There's nothing unique about _Deinodon_ at all?  That's depressing.
 
 
> > (and if we're not going to bother with
> > it, why not just sell it and the other nomia dubia - we already know 
> > there's a market)
> 
> Yeah, very funny. :-|
 
 Oh good, I was worried the required tone didn't come through.
 
 (though on a serious note, if nomia dubia have no scientific value, why bother 
with them?  (is it the Slippery Slope argument - if we let people buy nomia 
dubia, then they'll want to buy the scientifically valuable fossils too?))
 
 
 
> > I think I lost track of the thrust of the argument a few posts back.

> For the woes of the genus _Troodon_, the description of _Talos_ is
> worth a read (Zanno et al., 2011).
 
 I'll ask for it.