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non-avian "reptiles"




Scott,
It is certainly desirable to maintain "well-known" classifications if they are correct, but that is not one of my main priorities. Otherwise I wouldn't have named a new Class Scorpionea (for eurypterids and scorpions) back in 1994, and the definitive evidence for the holophyly of this group wasn't yet discovered (published in 1999). It was "well-known" in 1994 that scorpions are arachnids, but that certainly didn't stop me from sticking out my neck and going against what almost everyone else believed.
For me the best classifications have what might be called "heuristic value", and the cladistic maximization of predictivity is only part of that. Pure cladifications eventually suffer from some combination of complexity, instability, confusion, lack of utility, and certainly no way to reflect anagenetic information (divergence).
Cladists are fond of quoting Darwin wanting to base classification on phylogeny, but he also advocated reflecting divergence in classifications as well. And as for creating "equal groups" that will never happen, either based on any measure of diversity or stratigraphy (I think Hennig tried the latter and finally gave up). A mammal order will never equal an insect order, and there is no reason that they need to be. And I certainly would never removed Chiroptera from Mammalia just because they fly. They can't match birds in any measure of diversity that I am aware of, much less geological range.
Although I am an eclectist, I have found a way to nest groups without all the disadvantages of strict cladifications. Unfortunately when you try to explain this to either traditional eclecticists or traditional cladists, both sides think I'm "caving in" too much to the other side. But I don't see it that way----I view it as taking the best aspects of both systems, and at the same time trying to eliminate the disadvantages of both systems. Unfortunately the majority on both sides are so set in their ways that trying to find a fruitful middle approach is just too much trouble, even if they did think it was possible.
------Ken Kinman
*******************************************************
From: "Scott Hartman" <scott_hartman@hotmail.com>
To: kinman@hotmail.com, dinosaur@usc.edu
Subject: Re: Air sacs in extant non-avian reptiles?
Date: Tue, 01 Aug 2000 00:04:07 GMT

But on the other hand, I am not a strict cladist and have no desire to adopt Gauthier's cladistic Reptilia sensu stricto, and like most people, I regard synapsids as reptiles, and birds as a separate Class.<<<

Im not sure what the advantage of the "eclectic" style you are espousing. Surely the fact that it is "well known" isn't a good reason to change it ("No Mr. Darwin, although I'm sure you're right in essence, people just aren't familiar with 'evolution,' and it would only confuse students of natural history"). On the other hand, some people would argue that there is useful informational content (diversity levels???) in a hierarchal system. I won't argue that point, but if that is the case, you need to create consistent criteria so as to present "equal" groups, and by any criteria, you either have to sink Aves into Dinosauria, or else remove Chiroptera from the Mammalia. Either way, there is no legitimate reason to think of avian systematics in the sense that it is used in textbooks today.


Scott

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