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Re: Steadman's review of Mesozoic Birds

From: Nick Pharris <npharris@umich.edu>
Reply-To: npharris@umich.edu
To: dinosaur@usc.edu
Subject: Re: Steadman's review of Mesozoic Birds
Date: Sat, 31 Jan 2004 15:09:11 -0500

Quoting John Pourtless <vindexurvogel@hotmail.com>:

> Occam's Razor is one thing, but naive adherence to parsimony is another. It
> is a central tenet of cladistic analysis that convergence, parallelisms, and
> reversals are very rare and yet biologists working with extant and extinct
> forms have usually argued just the opposite.

But you can't just assume that if the characters uniting a proposed clade are
potentially due to convergence, parallelism, or reversal, then the clade is no
good, in the absence of evidence in favor of some other arrangement. That way
lies madness, since *any* character is potentially subject to convergence,
parallelism, or reversal.

Unless and until some evidence can be found showing that some ratites are closer
to neognaths than others, or linking one subset of ratites to one neognath
group and another subset to another neognath group, the hypothesis of ratite
monophyly remains the best game in town.

Nick Pharris
Department of Linguistics
University of Michigan

There already is evidence suggesting that at least some ratites (read tinmaous) are more closely related to neognaths.


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