Re: Sereno's (2005) new definitions

[David Marjanovic <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Jaime A. Headden" <qilongia@yahoo.com>
Sent: Saturday, December 24, 2005 11:32 AM

>  Here's some personal suggestions:
>
>  Theropoda = {Megalosaurus + Passer not Cetiosaurus, not Iguanodon}

Fine!

>  Neotheropoda = {Passer + Ceolophysis/Ceratosaurus}

*Ceratosaurus*. (And maybe a nonavian coelurosaur instead of *Passer*...)

If *Coelophysis* is outside of Neotheropoda, the name "Eutheropoda" suggests 
itself for {*Passer* + *Coelophysis*} (again another coelurosaur may be 
better). (In fact it has been suggested, but not published.)

>  Ceratosauria = {Ceratosaurus + Coelophysis + Abelisaurus not Passer}
> [conditional]

A potentially self-destructive definition... why shouldn't Ceratosauria be 
used (for {*Ceratosaurus* not *Passer*}) if *Coelophysis* is not included?

>  Coelophysoidea = {Coelophysis not Ceratosaurus}

Fine.

>  Neoceratosauria = {Ceratosaurus + Abelisaurus, not Coelophysis} 
> [conditional,
> I am not sure if this should not also exclude Dilophosaurus]

It should certainly exclude Tetanurae!

>  Ceratosauridae = {Ceratosaurus not Abelisaurus, not Coelophysis}

Sounds good...

>  Abelisauria = {Abelisaurus + Elaphrosaurus + Noasaurus}
>
>  Abelisauroidea = {Noasaurus + Abelisaurus, not Elaphrosaurus}
>
>  Abelisauridae = {Abelisaurus not Elaphrosaurus, not Noasaurus}
>
>  Noasauridae = {Noasaurus, not Abelisaurus, not Elaphrosaurus}
>  [Conditional, the topology (Abelisaurus (Noasaurus, Elaphrosaurus)) is 
> also
> possible]

In the latter topology Abelisauroidea would self-destruct, but nothing would 
happen to the others. Good luck on your phylogenetic analysis!

>  Tetanurae = {Passer not Ceratosaurus, not Ceolophysis, not Abelisaurus}

Good.

>  Neotetanurae = {Passer + Megalosaurus, not Baryonyx/Spinosaurus}
>
>  Avetheropoda = {Allosaurus + Passer}

This would make Neotetanurae self-destruct under the current standard 
phylogeny. I think Neotetanurae should be {*Allosaurus* + *Passer*}, thus 
(de facto) identical to Sereno's original definition (though maybe a 
nonavian coelurosaur would be better again), while Avetheropoda should be 
bigger than that.

>  Carnosauria = {Allosaurus, not Passer, not Megalosaurus, not
> Baryonyx/Spinosaurus}

Why would you exclude *Megalosaurus* and *Spinosaurus*?

>  Allosauroidea = {Allosaurus + Carcharodontosaurus + Sinraptor}

Fine (and identical to at least one published definition).

>  In ornithischians, the problem drastically increases

...largely because of the lack of serious phylogenetic analyses. This is 
changing as we write, beginning with Butler's SVP meeting abstract and his 
*Stormbergia* paper. So let's just wait till we get a better idea of which 
hypotheses are how robust. :-)

>  We have a long way to go before we start simply decided we are ata a 
> state to
> propose EASY definitions. I claim, as does Sereno, that we need TIME to 
> work
> the bugs, and not just declare a system that will avert many systematists 
> from
> using phylogenetic nomenclature.

I agree (and again recommend my recent proposal).