dinosaur taxonomy cont.

["Colette H. Adams" <cadams@hh.gpz.org>]

I'm glad to hear that paleontologists have no aversion to biology.  I'm
well aware that taxonomy above the species level is nebulous, even as it
applies to living species.  But I doubt many of us would try to live
without it.  The problem as I see it is this.  In order to make comparisons
between taxonomic groups such as dinosaurs, birds, mammals, etc., I must
use some taxonomic unit as a basis for comparison.  Let's say I wish to
compare the body size of dinosaurs with that of extant mammals.  I could
use the species as a unit of comparison, but many mammal genera have
multiple species.  This is particularly true among the smaller mammals.  So
a species-by-species comparison may be heavily biased.  Maybe I should try
genera.  But if dinosaur genera are mostly monospecific, I'm basically
comparing dinosaur species to mammal genera.  It is a problem and I suppose
there is no easy solution. 

But your interesting responses have evoked some thoughts.  

I take taxonomy above the species level to be about character variation,
nothing more and nothing less.  This does not make it less "real" than
species separations.  The two are about different things.  It happens to be
true that most species show some degree of character differentiation.  But
the issue of reproductive isolation does not bear on generic distinctions.  

With regard to the issue of credentials, I'm not sure what constitutes
"scientific" credentials.  I have a Master's Degree in Zoology, but I count
this an academic credential not a "scientific" one.  In any case, I
consider appeals to "credentials" to be no different in principle to any
other ad hominiem attack.  Scientific discourse should in my view address
the merits of the ideas being proposed, nothing more, nothing less.  

In my field many papers in peer-reviewed journals cite books, and even
popular magazines on occasion.  There is no particular effort to determine
whether a given book is peer reviewed or not.  The content is evaluated by
each author and each reader.  Nothing is accepted uncritically.

If someone has addressed each of the synomomies Greg proposed, on its
merits, that is enough for me.  No one is obliged to use his taxonomy.  I
realize that in many cases we are dealing with distorted and incomplete
original material, and there is a subjective component in comparisons. 

Even Greg has no more than 8 species per theropod genus, and the vast
majority of his genera are monospecific.  One wonders if this is a function
of the selective fossilization of dinosaurs.  I would be interested in
hearing any comments on this point.

Best regards,

Dave