Re: Another anatomy question

["Ray Stanford" <dinotracker@earthlink.net>]

    David Marjanovic wondered, "*Stegosaurus* has very high neural arches so
that the centra lie quite deep
in the body. Is there any hypothesis why? Thanks in advance for any answers.
:-)"

    Because of the reference to the centra lying "...deep within the
body...", I suspect David may have really meant to say neural SPINES,
instead of neural arches.  In Stegosaurus, the tallest neural spines are in
the sacrals and in the anterior-most caudals.  Therefore, it seems to me
that a reasonable deduction might account for the tall neural spines as
providing attachments for extensive musculature supporting motion from the
base of the caudals, as applied to move the end of the tail with its
dangerous spikes, as, e.g., in defense.  Also, the muscular attachments to
the tall neural spines of the sacral might have been necessary to manage the
kinetics of backlash (dynamics of angular momentum transfer) when the spikes
strike a target, or even when the 'weapon'  might suddenly snap loose, had
it been 'stuck' in its target.

    For anyone confused about the difference between a neural arch and a
neural spine:  A neural arch is the opening through bone that is located
above the vertebral centrum, per se, accommodating the spinal cord. A neural
spine is a bony spike that extends generally upward above the centrum, to
which muscles and/or tendons attach.

    Well, that's my two cents worth.  Does it help, confuse, or what, David?

Ray Stanford

"You know my method.  It is founded upon the observance of trifles." --
Sherlock Holmes in The Boscombe Valley Mystery

----- Original Message -----
From: "David Marjanovic" <david.marjanovic@gmx.at>
To: "The Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Tuesday, October 02, 2001 9:18 AM
Subject: Another anatomy question


*Stegosaurus* has very high neural arches so that the centra lie quite deep
in the body. Is there any hypothesis why? Thanks in advance for any answers.
:-)