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Re: cladobabble--here we go again



At 11:26 AM 11/14/97 -0500, Norm King wrote:

>Since the rise of phylogenetic taxonomy, we have changed the way taxa are 
>defined.  That means that taxa are now different things from what they 
>used to be.  Yet we still use the old names, as if we are referring to 
>the same kind of entity.  But we aren't.

I think there is a misunderstanding here.  American textbook standards
aside, there was very, very little standardization over taxonomic
definitions pre-cladistics.  People argued over whether mammals should be
defined by mammary glands, a single dentary bone, the jaw articulation,
other cranial features, etc.  Some even argued mammals were polyphyletic,
but we should use the name anyway.

Just because most of us are familiar with, and were taught, Colbert's and/or
Simpson's particular classifications doesn't mean that they were the
standards of professional paleontology and zoology of the early and
mid-century.  They were simply the guys who wrote the most commonly used
textbooks.

>I see this as one of the flaws in phylogenetic taxonomy.  There should be 
>only one way to define phylogenetic taxa.  Forget the praticalities--I 
>know the reasons why these three approaches to definition have been 
>taken.  Conceptually, the system of phylogenetic taxonomy is flawed in 
>that regard.  All taxa should be defined in the same way so they are 
>comparable entities.  (I admit, however, that I'd even settle for all 
>taxa within a phylum to be defined in the same way.)

Why should all taxa be defined as one type or another?  As long as they are
explicitly defined, isn't that sufficient?

Or should we extend this practice to petrology, and say that different rock
types can ONLY be defined by grain size?  Or ONLY by chemistry?  Or ONLY by
metamorphic grade?

>As a teacher, my biggest problem is finding a way to be current, yet not 
>snow my audience of lay people under a blanket of undecipherable 
>cladobabble.  The best approach seems to be to ignore the current 
>("proper"?) definitions for reptile and tetrapod, for example, and 
>explain what they are in the more traditional way.

This may work for you, but I find that my students can handle current
definitions very well.  (And, for the most part, my students are non-science
majors).

>This makes sense to 
>everyone rather than just to the academic elite, the latter of whom seem 
>to enjoy arguing about how many angels with Greek and Latin names can 
>dance on the head of a pin.  (Froth, froth, froth!)

I think we should go back to teaching miogeosynclines and stabilist
paleogeography...   Harumph! <g>

>Phylogenetic taxonomy has done some good things, but it has also created 
>a monster that did not exist previously

I REALLY suggest taking a look at the systematic literature of the earlier
parts of this century and then saying that this problem didn't previously exist.

>and is taking a lot of time and 
>intellectual effort to tame.
>
Hey, the pre-phylogenetic taxonomy took a couple of centuries.  For only ten
years, we've gotten a whole lot done!

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661