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Re: Revised Ornithischian Classification
No, I don't plan to write a paper. As I said in the recent disclaimer,
I am a classificationist, and simply attempt to act as a catalyst of sorts,
weaving conflicting cladograms, interpretations, and opinions, into a
classification that I hope gradually narrows down possibilities, encourages
more discussion, and perhaps along the way persuade a few more people that
carefully chosen paraphyletic groups can serve a valuable purpose (whether
they are recognized temporarily or permanently).
I do agree with Mickey that a more complete cladistic analysis of the
these various ornithischians (especially hypsilophyodontids) is badly
needed, and Pete and various others are working in this area. I personally
would love to see Mickey and Jaime get together and do such an analysis and
publish their results. The more analyses there are, the better, since
independent analyses can be used to correct each other and lead to even
better analyses. And also resolve some differences, such as whether
Tenontosaurus dossi makes that genus holophyletic or paraphyletic (Mickey
pretty persuasively argues that it is the latter).
In any case, I believe the scaled-down version of a paraphyletic
Hypsilophodontidae that I favor (with only one exgroup, namely the
dryomorpha clade) will be useful. The older and broader version of this
family (including genera like Agilisaurus and Thescelosaurus) was too broad
and too paraphyletic (also giving rise to heterodontosaurs and
If paraphyly is overused, not handled carefully, and not explicitly
labelled, cladists should be critical of such practices. But on the other
hand, reducing formal paraphyly to zero (automatic rejection of all such
taxa) is not only impractical, but too simplistic and philosophically
untenable in reflecting the complexities of evolutionary history.
From: "David Marjanovic" <email@example.com>
To: "The Dinosaur Mailing List" <firstname.lastname@example.org>
Subject: Re: Revised Ornithischian Classification
Date: Wed, 22 Aug 2001 00:22:36 +0200
> If I thought hypsilophodonts could be divided into two clades (as
> did), I would see no real need for a paraphyletic family. But the
> look, I see more and more small clades splitting off sequentially (far
> than 2).
While I have no opinion on this, could you tell us some evidence for this,
or are you planning to write a paper on it?
> Therefore, I believe it is strict cladification that is the bad
> idea in this case, because it would require perhaps 10 small families or
> more (there could be one or two Australian clades splitting off
> that would require more families).
...that's why I dislike ranks :-)
> Since most dinosaurologists continue to
> assign these forms to a Family Hypsilophodontidae,
Most dinosaurologists don't use families anymore, and Hypsilophodontidae in
such a broad sense at least has gone completely out of use in the last few
BTW, it's *Leaellynasaura*, with eae, after Lea Ellyn Rich AFAIK.
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