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more on criteria




Jaime,
I use so many criteria, and different combinations depending on the situation and on the taxonomic history of the group.
I do not use subjective criteria like "birds are better, more advanced, or more interesting". I personally think spiders are one of the most fascinating groups of organisms (more so to me than all the insects put together), and I've collected, studied, and photographed spiders for over 20 years. But I still only classify them as the single Order Araneida (one of 21 orders of Class Arachnidea). To me, mites seem totally boring, but I classify them in 7 separate orders because of their tremendous diversity and because "Acari" is probably polyphyletic.
I mentioned before that Dinosauria was considered polyphyletic in the past (Romer, Simpson, and others), and this view is still held by some (e.g., Feduccia). But even Feduccia recognizes the validity of the two separate orders of dinosaurs, and it is this relative certainty and lack of doubt that keeps me classifying dinosaurs as two separate orders. The synapomorphies unifying Dinosauria just seem more prone to homoplasy, but still strong enough that I continue to code the two orders as sister groups.
Overall balance can be an important consideration at times, but sometimes not (I'm not going to dump aardvarks in another order just because their Order is monotypic). Eclectic classifications tend to be more balanced and symmetrical than purely cladistic ones. Also more stable
and anagenetically more informative. And I would still like to see a purely cladistic classification of all organisms that is workable. I don't think it can be done, even if one were to ignore the problems of reticulation. In dividing the continuous tree of life, cladists are also making cuts that create paraphyletic groups, but they just don't realize it (or want to admit to it). Pretending that Eubacteria isn't paraphyletic, and the continued use of members of "Archaea" (= Metabacteria) as an outgroup to Eubacteria has bacteriology in a state of confusion. It's like using birds as an outgroup to reptiles, when they are actually part of the ingroup. I'm starting to ramble, so will stop here.
------Ken Kinman
*******************************************************
From: "Jaime A. Headden" <qilongia@yahoo.com>
Reply-To: qilongia@yahoo.com
To: dinosaur@usc.edu
CC: kinman@hotmail.com, ELurio@aol.com
Subject: Re: non-avian "reptiles"
Date: Thu, 3 Aug 2000 14:21:31 -0700 (PDT)

Ken Kinman wrote:

<I do recognize a clade Dinosauria informally (at the
end of my reptile classification---see below). I also
recognize a clade Synapsida informally (at the
beginning of my reptile classification----see below).>

  What are your criteria for formal clades? I had
understood, going way back, that both Synapsida and
Dinosauria were fully described, diagnosed, and valid
taxa.

  I do understand the need to recognize ranks in some
systems, for whatever artificial grouping is being
recognized might require "ranking" of development from
some sort of basal form. Eric Lurio points out that
birds are so derived as opposed to geckoes that they
must be relegated to a less-equal, "higher" rank to
reflect that so many more changes occured in one
(birds) than the other (geckoes). However, similar to
the original bloom of this classification scheme
(Linné [née, Linneus], 1785?), this reflected a sense
of some sort of superiority in life, that warm-blood
or feathers was better than whatever back-water,
chilly flesh might exist in those slinking, unholy
lizards [geckoes].

  There are herpetologists, I am sure, who work on
geckoes and whom find them the most fascinating
animals in the world. There are several unique
modifications in geckoes that are not present in _any_
other group of tetrapods (well, insects also have
hair-like extensions of the surface of _whatever_ that
allow them to walk up walls or on glass without
sliding). That's not counting many other features that
makes gekkonids much more unique than birds in many
respects -- including integument.

  So this comes down to some rather weighted choice
over what animal will be more advanced than another,
and using that as the scale upon which the
classification is based. Not recognizing the unbiased
development of animals relative to one another will
not consider who's better during evolution. In fact,
there will be no weighing: geckoes have as much
airtime as birds [I should use pigeons, but....] do on
the evolutionary course, considering development.
There's not need to say birds are better, unless there
is a _want_ to have better birds than lizards. Do you
think homeothermy is more efficient or a better
metabolic degree than poikilothermy or gigantothermy,
or that in any way a heater always turned on is better
than one that's only only when needed? There are some
decidedly bad drawbacks to being a homeotherm,
including excessive production of heat and high
metabolic rates of consumption and production.

  I personally do think birds are any better than
lizards, and have found some incredible diversity
(including flying animals) in the lizards and related
groups (*Icarosaurus*, *Kuhneosaurus*, etc.) that says
the birds don't have it all.

=====
Jaime "James" A. Headden

  Dinosaurs are horrible, terrible creatures! Even the
  fluffy ones, the snuggle-up-at-night-with ones. You think
  they're fun and sweet, but watch out for that stray tail
  spike! Down, gaston, down, boy! No, not on top of Momma!

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