RE: Ceratops (was RE: Pterosaur diversity (was: Re: Waimanu))

[Tim Williams <twilliams_alpha@hotmail.com>]

Mike Taylor wrote:

> 1. I think everyone agrees that, based on the type material, _Titanosaurus 
> indicus_ is not diagnosable from other titanosaurs, so that species, which 
> it was once valid, is now a nomen dubium.

I'm not sure I'm convinced that _Titanosaurus indicus_ is a nomen dubium.  
It all depends if you limit the name _Titanosaurus indicus_ to the type 
material only.  Wilson and Upchurch (2003) are not convinced that the 
titanosaur material from the type horizon can be demonstrated to come from a 
single individual or a single species.  But, if all the material from the 
_T. indicus_ type horizon is conspecific, then we could combine the 
_Jainosaurus septentrionalis_ material with the _T. indicus_ material, and 
we would have enough material on which to establish a valid genus.  This is 
more or less what Jain and Bandyopadhyay (1997) did.

> I think it's important that this change has happened not because of a 
> change in attitude to the original material, but a change in the context in 
> which it's evaluated, i.e. we now have dozens of
> sauropods with procoelous caudals, so that this character is no longer 
> diagnostic.

Yep.  But even the type mid-caudals for _T. indicus_ show characters other 
than just procoely.  The caudals are distinctive, but perhaps not 
diagnostic.  _T. indicus_ was considered a valid species long after it was 
realized that strong procoely in the middle caudals had a wider 
distribution.  Wilson and Upchurch discuss this, and dismiss six features 
previously used to diagnose _Titanosaurus_.

> 2. I think everyone also agrees that since _Titanosaurus indicus_ is the 
> type species of _Titanosaurus_, that genus is no longer valid.

Yes, there is no wiggle-room here.

> It is clear that no article of the draft PhyloCode prevents us from 
> continuing to use Titanosauria.
> But I still feel a bit queasy about it -- maybe because I am offended that 
> different rules seem to govern Titanosauria and Titanosauridae.

I'm perfectly at peace with this.  I'm also OK with Ceratopsia persisting as 
a clade even if _Ceratops_ is a nomen dubium.  I guess the reason I feel 
this way is that -idae does have a specific meaning, and it should be 
mandatory that the eponymous genus is included.  In other words, -idae is 
not an arbitrary suffix the way -ia is.

> In my fantasy world, the ICZN continues to govern species and genera, and 
> the PhyloCode foreswears all intention of messing with them.  In return, 
> the ICZN gives up families and the related ranks, leaving the PhyloCode 
> free to govern all clade-names without interference,
> irrespective of their endings.  But, hey, that's just _my_ fantasy.

No, it's my fantasy too.  At least with respect to the respective 
jurisdictions of ICZN versus PhyloCode.  As for butterscotch sauce... it all 
it does is make me very hungry.

> > Yes.  After all, rigorously establishing the affinities of taxa is
> > the main purpose of PT.
>
> Hahahahahahahaha.
>
> Oh, sorry.  That wasn't a joke, was it?

This is the ostensible "purpose" of PT, isn't it?  Whether this purpose is 
actually accomplished is a totally different kettle of fish.

;-)

Cheers

Tim