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Re: DEFENDING MODERN BIOLOGY



At 04:59 AM 6/21/00 -0400, Tetanurae@aol.com wrote:
This is a statement that is a highly practiced staple of debate with people
that don't know better.  Certain unmentionables often mention that "such and
such" is so obvious that a small child could tell said fact, in an effort to
undermine their opponent's arguments.  ...

I agree that being "obvious to a small child" is not scientifically relevant. But that is hardly the main argument in favor of allowing paraphyletic groups.


are VERY different and that whales do not even belong in this group.  The
term Mr Kinman uses, "highly derived clades" is simple exageration.  I
believe that snakes and whales are very much highly derived clades and under
Kinman's rules should be subject to exclusion from Reptilia and Mammalia
respectively.

True, Mr. Minman's rather vague "highly derived clades" does allow that. A more precise definition of when and how a clade is sufficiently "highly derived" to require separation is needed. This definition has been provided by Dr. Peter Ashlock. I used it in deriving my classification of Theropoda on my Website from Dr. Holtz's cladograms.


Seperating mammals and birds as different and "better" is what Linnean
taxonomists had been doing for 200 years.

Umm, not good ones, at least not in the last century. Different they are, but removal of these groups from Reptilia does NOT imply they are better.


  By insisting on using paraphyletic
taxa, the lay-people that Kinman claims to be a champion of get the
impression that somehow Velociraptor is much more similar to Archelon and
Dimetrodon than it is to Corvus because they are all three reptiles and the
latter is not.

I cannot speak for Mr. Kinman, since he uses subjective categories, but the mere use of paraphyletic categories, especially if based on information content, does *not* in itself champion any such view.



For this very reason (as well as arbitrary ranking of groups), cladistics in
general and phylogenetic taxonomy in particular, have gained a lot of ground.

At a cost - at a loss of stability and of general utility (and in many forms with an excessive proliferation of names). Clasdistic definitions of the forms now used allow nearly complete changes in the membership of a taxon, which would make the taxon useless as an index into the literature. (A good case of this is the situation with regard to Ornithosuchia).


 <<In the strict cladist's world, classifications must be purely
 genealogical, no matter what the cost.>>

How else would you like your classifications to be?  Size based?  Locomotor
based?  Eye color based?  EVERYONE'S classification systems are
geneologically based.  The thing that PT is trying to move away from is the
subjective splitting and ranking that has been the hallmark of Linnean
systematics.

There are other alternatives! One can avoid the most of the subjectivity simply by following Dr. Ashlock's methods! Dr. Ashlock's methods are at least as objective as strict cladistic methods, especially where cladists avoid naming every node.


How do you quantify divergence?  How does your subjective opinion get turned
into objective observation?  How are birds more different from theropods than
snakes are from varanids?

While Mr. Kinman makes no proposal about this, Dr. Peter Ashlock gives you a method for doing *exactly* that. (It is possible that when properly analyzed by his methods it may turn out that snakes *do* deserve to be coordinate with Reptilia, not subordinate to it, though I doubt it).



Of course you can create paraphyletic groups Mr Kinman, but why do you need
to?

See my Web page. I have several pages of reasons. http://people.we.mediaone.net/sarima/dinosaurs/ (See the subsection on taxonomic philosophy).

Actually, I should ask why would you *want* to?

Ditto.

  How are trash-can
non-clades at all informative?

What makes properly diagnosed and analytically derived paraphyletic groups trash-can taxa? (Most trash-can taxa I know of have turned out to be *poly*phyletic).


  Where is the objectivity in choosing such and
such animal or such and such character because you think it's more derived?

Check Dr. Ashlock's methods.

--------------
May the peace of God be with you.         sarima@ix.netcom.com