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RE: Pterosaur origins

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.




        Christopher Taylor

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