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Nitpicky cladistics



This comment by Tom Holtz (11/15/96; 10:06a) intrigues me:

>The word "Maniraptora" BY DEFINITION includes the birds!

It is my sense that birds have not been conclusively shown to be
descended from deinonychids or any other dinosaur.  So, since we can't
demonstrate it by the evidence, can we really get around that by DEFINING
it to be the case? (Yes, I know the prevailing opinion in this group, but
my question is conceptual.)

Wouldn't a non-cladistic taxonomic category still exist if part of it
were removed?

>If you choose not to use a cladistic taxonomy, then please do NOT use
>the word "maniraptor".

What happens to maniraptor if you use cladistics to make a case that
birds are descended from an ornithosuchian?  (Granted, that would require
some new fossils to be found, but, again, the question is conceptual.)  I
assume one could define a new cladistics-based category, perhaps the
"Thecoavia" or even "Ornithornithia," which, BY DEFINITION would include
birds.

Cladistics-based taxonomic categories seem poised to dictate our concepts
of reality, whereas it should be our concepts of reality that dictate the
taxonomic categories.  Cladists have become prisoners of their own rules.
 Non-cladistics-based taxa are superior from the standpoint of not
requiring any particular view of the course of evolution to be valid.
Perhaps "bird" should be kept separate, being descendants of maniraptors
(defined differently).

Maniraptora seems to be a legitimate grouping of dinosaurs, whether one
uses cladistics or not, or whether birds are included or not.  So, any
non-cladist ought to be able to use it.  It's not a forbidden term for
them.  They might have to redefine it, but that happens all of the time
in taxonomy.  No reason why it can't happen to terms established by
cladists.

Have I missed something here?    :-S ?

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Norman R. King                                       tel:  (812) 464-1794
Department of Geosciences                            fax:  (812) 464-1960
University of Southern Indiana
8600 University Blvd.
Evansville, IN 47712                      e-mail:  nking.ucs@smtp.usi.edu