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Re: coelurosaur phylogeny & classification



David,
First, I just noticed that I used the term "outgroup" where I meant "exgroup"----that one parenthetical phrase should read "combined into one *exgroup* and thus one marker". And I've decided to plug in Plesion _Bagaraatan_ between Ornithomimidae and Therizinosauridae, but I'm still not convinced that it shouldn't be in Coeluridae.
Now responding to David, "wastebasket" is a subjective term, and I only use it for groups I am convinced are polyphyletic (or so paraphyletic as to be counterproductive----such as Lophotrochozoa or Condylarthra). What is important is that it is organized in some way that imparts information. Mike Keesey and I organize our wastebaskets differently.
The {{Ornithomimidae to AVES}} clade seems to be cladistically equivalent to Maniraptoriformes Holtz (1996?). I don't feel compelled to name it, but since it has been named, I put in this synonymy. Since the contents of "Maniraptoriformes" depends on whose cladogram you are using, I prefer to informally refer to it as the maniraptoriform clade.
I could formally split Saurischiformes into two separate orders, but a theropod order could be paraphyletic to a sauropodomorph order, which would make theropods doubly paraphyletic (to Aves and sauropodomorphs) or even triply paraphyletic if Ornithischiformes is a theropod exgroup. I am simply minimizing paraphyly and using traditional groupings as well. I code the two dinosaur orders as sister groups, but such a united clade doesn't have any unequivocal synapomorphies and also has a shorter history of usage as a formal taxon (I may formally combine them into one order eventually, but not yet).
And I do plan to use plesions (or is it plesia?) a lot more. I could do this as Mike Keesey does in Dinosauricon, but traditionalists often prefer to group a cluster of basal "plesions" ("plesia"?) into a single paraphyletic taxon like Coeluridae (with one or more exgroups) when there is almost no consensus as to how they are all interrelated. There is no concise way to impart such lack of information---I think mine is more flexible, more acceptable to traditionalists, discourages destabilizing splitting, and formally recognizes the reality of paraphyly.
There's more than one way to skin a cat, and I continue to explore for ways to balance the traditional cladistic and eclectic approaches, and perhaps speed up the process of their inevitable synthesis into one system.
------Ken
P.S. Now let's see, where to place Protarcheopteryx? As the basal genus of Caudipteridae? Or a plesion somewhere else in the maniraptoriform clade? Any suggestions??
********************************************************
From: "David Marjanovic" <david.marjanovic@gmx.at>
Reply-To: david.marjanovic@gmx.at
To: "The Dinosaur Mailing List" <dinosaur@usc.edu>
Subject: Re: coelurosaur phylogeny & classification
Date: Tue, 29 May 2001 12:51:04 +0200

> Dear All,
>        I've concluded that the basal relationships of coelurosaurs is so
> uncertain (and bound to remain so for a long time)

sure

> that the best
> cladisto-eclectic approach would be to return to the recognition of a more
> traditional, broad "paraphyletic" Family Coeluridae (rendered
> semi-holophyletic with markers).


URGH!!! This is quite a wastebasket, IMHO. Why not list the members under
"incertae sedis" (as in the Dinosauricon)?

> [...] (Note that _1_ is the only symbol which interrupts a
> cladistic sequence and marks the beginning of another major clade):

I think I've understood it, but that's difficult to read, you know...

> ORDER SAURISCHIFORMES
>           .....basal families omitted here

Here the main disadvantage of having few ranks, compared to many ranks (let
alone no named ranks). If you stick to calling Saurischia an order (why not
follow Bakker & Galton and call it a subclass of Class Dinosauria?), you
have to lump all sauropods, prosauropods and theropods together... :-( .

>            9  {{Ornithomimidae to AVES}}
>                   (= Maniraptoriformes Holtz?)

See, you need a name, you want a name, but you can't give a name in your
system... B-) :->

>     6  Plesion _Rahonavis_

What do you mean with "Plesion"? A genus that doesn't need to be put into a
family? IMHO you should apply this much more often...

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