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Re: eggshells, therizinosaurs & tyrannosaurs



On Wed, 19 Jul 2000, Ken Kinman wrote:

>      I can understand why Sereno's neologisms might irritate you, but given 
> human nature and the peculiarities of phylogenetic taxonomy, it's bound to 
> happen again and again.

This is being taken under consideration for PhyloCode
<http://www.ohiou.edu/phylocode/index.html>.

> And anchoring a taxon like Ceratosauroidea on a genus other than
> Ceratosaurus (after which it is named) is just asking for trouble.

Total agreement.

> I think this has already happened with Ornithosuchia, which according
> to many phylogenies no longer includes Ornithosuchidae (type genus
> Ornithosuchus).

Excellent example. (Wasn't that one also Sereno's?)

>  Just one more reason for me to dislike such anchoring.

But if they were anchored on the eponymous genera (or specifically, on the
type specimen of the type species of the eponymous genera), would there be
a problem?

>      But however messy Sereno's naming practices might be, I do find his 
> dinosaur phylogenies to my liking so far, although I am reserving judgment 
> on the Alvarezsauridae placement (but I don't think anyone can be sure about 
> that family's affinities at the present time).

I agree in general.

>       Anyway, this demonstrates how phylogenetic taxonomy can increase 
> confusion, rather than minimizing it, even in the long run.

No, only that misusing it can create confusion. The same goes for
traditional taxonomy.

> Sorry, but I still think an occasional semi-paraphyletic 
> group is preferable to a purely cladistic Tower of Babel.

It's only a Tower of Babel when priority is ignored or definitions are
made not considering alternate phylogenies.

Membership changes. Gauthier's original Maniraptora has become more
inclusive under newer phylogenies. But I don't think that undermines the
definition.

You just have to remember that phylogenetic taxa are based on
phylogeny; not on characters (except for apomorphy-based taxa) and not on
vague notions of "degrees" of relatedness.

> In any case, the point is that the literature is going to be full of
> references to different concepts of Maniraptora that will cause lots
> of future confusion,

I don't think Sereno's definition has supplanted Gauthier's. You are
really arguing more against Sereno's re-definition than against PT as a
whole here. (And I agree.)

> and that doesn't even include those cases that don't distinguish
> between "non-avian" Maniraptora and the broader cladistic Maniraptora.

There is only cladistic Maniraptora. It was coined by Gauthier as a
phylogenetic taxon, and has not been used, TMK, in traditional taxonomy.
Excluding Aves from Maniraptora would undermine the entire original intent
of the taxon, to show that birds and dromaeosaurids share more recent
ancestry with each other than with ornithomimids.

____________________________________________________________________________
T. Michael Keesey <tmk@dinosauricon.com> | AIM <Ric Blayze> | ICQ <77314901>
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