Re: CRANIAL-CAUDAL vs ANTERO-POSTERIOR

["Jerry D. Harris" <dinogami@hotmail.com>]

In an extremely rare and minor technical error, Darren wrote:

> (and a cranial caudal vertebra would have to be called an anterior
> caudal vertebra in the 'old' system anyway).

  My understanding is that, in the tail, one does not use the terms 
"cranial" and "caudal" -- one uses "proximal" and "distal" instead.  Thus, 
there are no "cranial caudal vertebrae;" there are, however, "proximal 
caudal vertebrae."  I cannot, however, at this moment, put my finger on the 
source of that, although as previously noted, Larry Witmer noted this point 
to this list (Oct. 16, '98).

  Just for everyone's edification, "anterior" and "posterior" now have only 
an extremely limited usage in modern anatomy (and since fossil organisms are 
related to modern ones, there is no good reason to have different terms for 
each!).  To wit, for birds (upon which much dinosaurian anatomy should be 
based, terminologically speaking), _Nomina Anatomica Avium_ states:

"Cranial and caudal are used throughout the [_NAA_], except that rostral 
replaces cranial within the head from the level of the occipital condyles. 
Superior and inferior are entirely avoided, but the prefixes supra- and 
infra- are retained for convenience and because of long usage, e.g., Nervus 
infraorbitalis. Anterior and posterior are used only in the eye and 
ear...but again the prefix post- has occasionally been used in terms which 
are well established, such as Ligamentum postorbitale...That some anatomists 
stronlgly prefer anterior and posterior as general alternatives to cranial 
and caudal is recognized, because these are time-honored terms in the 
literature of vertebrate morphology. However, these terms can be confused 
through their entirely different meaning in human anatomy, where they refer 
to ventral and dorsal. Anyone not convinced of this potential confusion 
should examine the anatomical writings of the eminent nineteenth century 
prosectors of the Zoological Society of London...Although writing as 
zoologists in zoological journals, these authors commonly used anterior and 
posterior in the human sense. Sometimes the usage of human anatomy and the 
zoological usage were both employed in the same paper...Even so, it is not 
realistic to expect the instant and universal adoption of cranial and 
caudal; nevertheless, it is hope that eventually this will be achieved."

  _Nomina Anatomica Veterinaria_ is much more protracted in its discussion, 
but says this:

"Anterior, posterior, superior, inferior. These terms cannot be generally 
applied to quadrupeds because of the confusion arising from their meaning in 
human anatomy. The use of these terms is restricted to some structures of 
the head."

  There will, of course, be resistance to learning and applying the new 
usage, particularly among those who have the "old" system ingrained in their 
thinking.  The same can be said of those who have rallied against the 
phylogenetic systematic/cladistic terminology in lieu of the established, 
long-used Linnaean system, but in either case, all it takes is a bit of 
practice, and an understanding of the shortcomings of older systems that the 
newer systems attempt to alleviate, and they too will become second nature.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jerry D. Harris
Dept of Earth & Environmental Science
University of Pennsylvania
240 S 33rd St
Philadelphia PA  19104-6316
Phone: (215) 573-8373
Fax: (215) 898-0964
E-mail: jdharris@sas.upenn.edu
and     dinogami@hotmail.com
http://www.sas.upenn.edu/~jdharris

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