Re: Dino Birds (was Re: Dinosaur = extinct animal)

["T. Mike Keesey" <tkeese1@gl.umbc.edu>]

On Tue, 20 Jul 1999, Stanley Friesen wrote:

> At 12:10 PM 7/19/99 -0400, T. Mike Keesey wrote:
> >See? You're still sacrificing one for the other, when, objectively, each
> >is just as useful as the other.
> 
> I don't agree that they *are* all equally useful.  Those that encode ore
> information have greater utility than those that imply little information.

How can you calculate this?

> Clade Coelurosauria minus Clade Maniraptiformes is just NOT very useful.

I disagree. I use the term "basal coelurosaurs" quite a bit.

> There are very few things indeed that can be said to be exclusively true of
> that paraphyletic group.  On the other hand, there is a great deal one can
> say about Clade Coelurosauria minus Clade Avialae, as it the organisms in
> it are ecologically rather closely allied.

Since when is ecology an element in either traditional or phylogenetic
taxonomy?

Ornithischians and Sauropodomorphs are ecologically distinct from other
dinosaurs, being plant-eaters instead of carnivores or insectivores. Why
not cut them off from Dinosauria?

> (Yes, there is some question as
> to where the best partition puts the Saurornithurae:
(You mean Saururae?)
> on the avian or the dinosaur side of this split, but for now I treat
> them as being on the avian side). 

See, I don't see how you can decide which one place is the "best" one to
cut. Why cut at Ornithurae or Avialae? Why not Carinatae or Maniraptora or
Paraves or Pygostylia?

> >No constant, arbitrary revisions necessary.
> 
> Actually, every new cladogram introduces a revision in my experience, even
> if most names are retained.  A properly information-intensive Linnaean
> classification can remain unchanged even if the cladogram changes.  For
> instance, in the Linnaean system I can retain Prosauropoda as a taxon
> *with* *the* *same* *membership* regardless of whether it is monophyletic
> or paraphyletic.  That strikes me as being less revision than making it
> synonymous with Sauropodomorpha if the traditional prosauropods turn out to
> be paraphyletic (which is the cladistic solution)

But it *should* change. If a new discovery or interpretation is made, why
should the classification continue to reflect the old way?

I believe Prosauropoda is defined as a stem taxon (=={_Plateosaurus_ >
_Saltasaurus_}?) If, for example, _Thecodontosaurus_ is found to lie
outside, why shouldn't we exclude it?

--T. Michael Keesey
tkeese1@gl.umbc.edu | THE DINOSAURICON: http://dinosaur.umbc.edu/
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