RE: The iguanodont paper

[Tim Williams <twilliams_alpha@hotmail.com>]

I don't have too much to add to Mike Keesey's excellent response, but this 
Thecodontia thing deserves special attention...

Greg Paul wrote:

> Thecodonts could be archosauromorphs excluding dinosauromorphs
> and pterosauromorphs (and perhaps crocodylomorphs, although it could be argued
> that they are the last surviving thecodonts).

Oh God, no!  "Thecodontia" was consigned to the dustbin over 20 years ago.  
Let's leave it there, buried beneath the banana peels and snotty tissues of 
typological thinking.

> The revival of a name that conveniently labels the basal archosaurs is not
> going to adversely impact the bird origins controversy. For one thing, the
> anti-dinosaur people are detached from reality anyway so they are going to do 
> what
> they do no matter what is done with the taxonomic system. 

That's true.  But why make it easy for them?  Thecodontia was the fig leaf that 
disguised the ugly truth of the BANDit philosophy: that the anti-dinosaur 
people didn't have a clue which particular thecodont was closest to the origin 
of birds.  Now, with the abolition of "Thecodontia" as a valid taxonomic group, 
the BANDits are forced to fumble around for an alternative to "thecodont" as 
their hypothetical bird ancestor.  So why hand Thecodontia back to them on a 
platter?  If Thecodontia is resurrected under the auspices of phylogenetic 
nomenclature, then it once again becomes a convenient term for the BANDits to 
hide behind.  It's a retrograde step.  

Beside all that, the blanket term "Thecodontia" doesn't do justice to the sheer 
morphological (and phylogenetic) diversity represented by the basal archosaurs 
and basal archosauromorphs.  You're lumping together critters like _Effigia_ 
and _Euparkeria_ and _Stagonolepis_ and _Postosuchus_ - and even the 
crocodilians as well, if I understand you correctly.

> Also, basal
> archosaurs are also defined by the exclusion of dinosaurs and pterosaurs, so 
> there is
> no practical difference except that the current system is linquistically more
> awkward.

Linguistically awkward it is, but such terms are also very explicit.  You know 
exactly where you stand with terms like "non-dinosauromorph, 
non-pterosauromorph archosaur".  "Thecodontia", on the other hand, could be all 
things to all people.  

Having said all that, I'm really looking forward to the revisions of those 
other iguanodont (a.k.a. non-hadrosauroid iguanodontian) taxa.

Cheers

Tim
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