Re: Croc classification (was Re: Sarcosuchus and Dumbing things down)

["Steve Salisbury" <steve_salisbury@bigpond.com>]

Some parts of the previous chain have been deleted.

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>From: chris brochu <cbrochu@blue.weeg.uiowa.edu>
>To: dinosaur@usc.edu
>Subject: Re: Croc classification (was Re: Sarcosuchus and Dumbing things down)
>Date: Tue, 30 Oct 2001 2:48 PM

> Crown groups have a number of benefits, one of which is stability -
> and here is where I really think Steve Salisbury is missing the point
> of stability.  We can never achieve stability of content, which is (I
> think) what he meant by "Crocodilia in the old sense had stability" -
> everyone agreed on the content.  I disagree with that (witness his
> agreement with me that the lower bound of "Crocodilia" was poorly
> defined), but more importantly disagree on whether everyone agreed on
> the underlying  *meaning* of Crocodilia.

> The truly important point is that phylogenetically-defined names have
> stability in meaning; stability in content, in diagnosis, and in time
> of origin can never be stable (under ANY taxonomic system)

Eh?  How can a cladistically defined name have meaning in a
non-cladistically based taxonomic system?  The truly important point is that
there is more than one set of rules.  There's also more than one game, and
no one should be telling us which one we have to play.

At the end of the day (and hopefully this chain!) it all depends on whether
you believe taxonomies should reflect phylogenies.  I don't think taxonomic
categorisations have anything to do with phylogeny or, for that matter,
evolutionary transformations.  To my mind, taxonomic definitions that rely
on assumptions of relationship are therefore meaningless (sorry Chris).
Taxonomies are much easier to defend when they don't involve phylogenetic
presuppositions.

Steve

---------------------------
Steve Salisbury

Palaeontology and Geology, Queensland Museum
PO Box 3300, South Brisbane, Q 4101, Australia

www.Qmuseum.qld.gov.au