The "Great" Cladistic Debate

["Matthew Bonnan" <mbonnan@hotmail.com>]

Hi all:

Just a quick remark about the past few days of cladobabble on the dinolist.  
It seems to me (IMHO) that the problem that arises between "cladists" and 
"non-cladists" boils down to misunderstanding the probablistic nature of 
science and what we do as paleontologists.

It has been argued by folks who use cladistic methodology that the Linnean 
System of Classification has reached its end.  You cannot divise enough 
catagories to keep up with the rate of studies and findings in our field.  
This is where probability comes into play.  The nice thing about using 
cladograms to express systematic hypotheses is that they express a 
probabilistic outcome of dinosaur relationships.  Every hypothesis and 
theory in science comes down to probability, and so a cladogram represents a 
probabilistic, testable, and TEMPORARY hypothesis, a generalized statement 
or idea from which future research springs.  With the Linnean System, you 
don't get to express your data as clearly as that, and we are always dealing 
with the problems of categories vs. continua.

On the other hand, some people get lost in the drive to find more characters 
without rigorously evaluating those characters and what they imply 
functionally, paleobiologically, etc.  This is where I see the most conflict 
and problems.  Like my shoulder example earlier, we need to exert a special 
effort to carefully evaluate the characters we pick.  Certain characters can 
have a large effect on the outcome of a cladogram, and since our cladograms 
drive our future research, we must excercise as much caution as possible 
when picking characters, a decision that is hopefully based on 
considerations of functional convergence, paleobiological data, etc.

At base, when used appropriately, the cladistic method allows us to present 
our genearlized ideas about dinoaur relationships, show and explain the 
characters we picked to do this, and suggest areas of inquiry in both 
systematic studies and paleobiological ones.  The Linnean System served us 
well for many years, but it is a dated system with less to offer us in terms 
of testability and repeatability now.  We will never get "the cladogram" of 
dinosaur relationships, but we can strive for cladograms that have a high 
probability of accurately reflecting the relationships among the dinosaurs.

Over and out,

Matt Bonnan
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