RE: Pterosaur origins

[Tim Williams <twilliams_alpha@hotmail.com>]

Chris Taylor wrote:

> Under the ICZN rules, Coeluroidea would have priority over Tyrannosauroidea 
> if one chose to recognise a superfamily uniting _Tyrannosaurus_ and 
> _Coelurus_, yes. Of course, no-one is under any obligation to do so - you 
> could just as easily recognise two superfamilies Coeluroidea and 
> Tyrannosauroidea that happen to be sister taxa (though in this case, 
> Coeluroidea would currently be redundant with Coeluridae).

Tyrannosauroidea currently has at least one phylogenetic definition.  By 
contrast, Coeluroidea has none (AFAIK).  So under the principle of "first 
in, best dressed", Tyrannosauroidea would win out.  Even though, as you say, 
under ICZN rules Tyrannosauroidea should be a junior synonym of Coeluroidea.

If one wants to retain Coeluroidea and Tyrannosauroidea as separate and 
mutually exclusive taxa ("superfamilies"), then this could be achieved by 
using the nominative genus of the *other* superfamily as an external 
specifier.  A new clade (e.g., Tyrannosauria) could be erected, and defined 
to be a more inclusive taxon - such as _Tyrannosaurus_ but not _Passer_ 
(stem-based).  The name Coeluria is available, of course - but it's 
traditionally (and fairly recently - Paul [1988]) been used for something 
totally different.

> Personally, I'd probably be cautious of sinking Tyrannosauroidea into 
> Coeluroidea unless the support for uniting them was very strong.

Me too.

Cheers

Tim






>     Cheers,
>
>         Christopher Taylor

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