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Re: eggshells, therizinosaurs & tyrannosaurs





Mike,
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. And anchoring a taxon like Ceratosauroidea on a genus other than Ceratosaurus (after which it is named) is just asking for trouble. I think this has already happened with Ornithosuchia, which according to many phylogenies no longer includes Ornithosuchidae (type genus Ornithosuchus). Just one more reason for me to dislike such anchoring.
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).
Anyway, this demonstrates how phylogenetic taxonomy can increase confusion, rather than minimizing it, even in the long run. A productive discussion about characters can get so easily side-tracked by these nomenclatural problems. And wherever there is an unnamed node, at least one person is probably going to attach a name to it eventually, and the problems are compounded. Sorry, but I still think an occasional semi-paraphyletic group is preferable to a purely cladistic Tower of Babel.
------Ken Kinman
P.S. And Jaime, I don't think I said Sereno coined a new definition for Maniraptora----just that he was not following Gauthier's definition. If he did follow it, I believe that his Tyrannoraptoria would include the same taxa (at least in his 1999 phylogeny). 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, and that doesn't even include those cases that don't distinguish between "non-avian" Maniraptora and the broader cladistic Maniraptora. I know cladists think things will calm down and get better eventually, but I think this is wishful thinking.
Although I object to purely cladistic classification on theoretical grounds, the way it is being practiced makes me even more convcinced that it causes more problems than it solves.
******************************************************
From: "T. Mike Keesey" <tmk@dinosauricon.com>
Reply-To: tmk@dinosauricon.com
To: -Dinosaur Mailing List- <dinosaur@usc.edu>
Subject: Re: eggshells, therizinosaurs & tyrannosaurs
Date: Wed, 19 Jul 2000 15:01:50 -0400 (EDT)

I realize what I wrote earlier might come off as a slur against Sereno,
and so I had better qualify my observations ...

> > According to my observations, Sereno doesn't have much respect for
> > priority

One example was what sparked these comments. He defined Maniraptora as a
node-based group after it had already been defined as a stem-based group.
(I do think that node deserves a name.)

> > (even his own)

IIRC, he replaced Cerapoda with the name Neornithischia.

> > eponymity

IIRC (again -- sorry, I'm away from any literature), he anchored
Ceratosauroidea with _Coelophysis_. This makes it so _Ceratosaurus_ is not
necessarily a ceratosauroid.

>, or the possibility that someone else's phylogeny might be more correct.

He created a node-stem triplet of Ornithomimoidea and its two subclades,
Alvarezsauridae and Ornithomimidae. Under more conventional phylogenies
(where _Alvarezsaurus_ is an avialan), his Alvarezsauridae becomes
equivalent to Maniraptora (by the original definition, not his),
Ornithomimoidea becomes equivalent to Maniraptoriformes, and
Ornithomimidae becomes equivalent to Arctometatarsalia (and, incidentally,
also to Ornithomimosauria _sensu_ Sereno).

I'm not trying to personally attack anyone but I do strongly disagree with
many (but not all) of Sereno's practices with regard to phylogenetic
taxonomy.

____________________________________________________________________________
T. Michael Keesey <tmk@dinosauricon.com> | AIM <Ric Blayze> | ICQ <77314901>
My Worlds <http://dinosauricon.com/keesey>
The Dinosauricon <http://dinosauricon.com>



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