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Some clarification (was Re: cladobabble--here we go again)



At 08:51 PM 11/17/97 -0600, Chuck Prime wrote:

>About the only thing I know about cladistics is that it is an intellectual
>method of classifying (certain?) animals. As such, the CLADE is an
>epistemological tool which does not exist in material form--even though
>papers outlining it do, the fossils referred to by it do, the animals who
>were fossilized did...

Actually, a clade (from Greek clados, branch) is any monophyletic group: an
ancestor and all its descendants.  Accepting, based on other data, the
existence of evolution as modification with descent, there exist real clades
in nature external to human reality.  We can propose names for real clades
based on the relationship of any two taxa (or one character, but (as
discussed earlier) there is a chance of homoplasy spoiling such
definitions).  Clades defined by the relationship of any two taxa (stem- or
node-based definitions) have reality in fact, unless one or both taxa are a)
specially created; b) aliens or otherwise not part of Earth's biota by
descent or c) imaginary.

One goal of systematics, then, is to determine (based on a particular data
set) what are the characters which diagnose these clades and what are the
component taxa of these clades.

Hoping this helps.

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