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More problems with "Unified Cladistics"



One last post on this subject by me today:

Something laymembers of the list might not be aware of is that there is
still some debate about the homologies of various bones in particular fossil
taxa.  This is NOT so much a problem in dinosaurs at present (okay, the
finger thing in theropods...), but in some other fossil verts it is most
certainly the case!

A good example of this is the postorbital region of ichthyosaurs: there are
two camps who disagree over whether a certain bones are supratemporals or
squamosals or new ossifications or whatnot.  Since there still remains
observational differences about this topic, how can there be an accepted
Universal Data Set for Ichthyopterygia?

(For what it is worth, John Merck's disseration and post-disseration work is
showing that this difference in postorbital bone homology identification
doesn't actually affect the position of ichthyosaurs within the Diapsida,
but that is another topic for another time).

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-314-7843