From: news@fedfil.UUCP (news)
Newsgroups: talk.origins
Subject: Friesen on elastics and sauropod necks
Date: 29 Sep 92 01:20:17 GMT
Organization: HTE


From: swf@teradata.com (Stanley Friesen)

|
|      Tension
|     in the ligament holds the head up, relieving the epaxial neck
|     muscles of much of the burden.  Furthermore, when the hypaxial
|     muscles contract, depressing the head, the ligament is stretched.
|     Because of its low Young's modulus, the nuchal ligament stores a
|     large amount of strain energy, and since it can be extended fairly
|     easily the ligament allows for a fairly large range of motion.
|     When the muscles relax, the strain energy is released, assisting
|     the epaxial muscles in elevating the head.

|  Now Ted, in case you didn;t understand this moderately technical description,
|  McGowan just said that ligaments are *elastic*, like rubber.  (That's what
|  "low Young's modulus" means.

The reality is that nothing of flesh and blood could hold the torque 
involved with the notion of holding a sauropod neck out near horizontally.

Again, scientists are now claiming that sauropods held their necks out
horizontally because they'd not have been able to get blood to their
heads were they to hold them as high as the bones would appear to allow for.

This would generate a torque load easily in the hundreds of thousands of
foot-lbs;  for instance, if a 360,000 ultrasaur's neck were to weigh
30,000 lbs from the shoulders outwards, and that seems conservative, and
if the center of gravity of that neck were ten feet out from the shoulders,
he would have to deal with 300,000 ft-lbs of torque to hold his head
out horizontally as scientists are now claiming.

Stanley is now claiming elastic ligaments did the job.  Try an experiment,
Stanley:  Get yourself one of the rubber-powered toy aeroplanes flown either
in open competition or in the Wakefield cup events, wind the rubber all the 
way, tie the prop agianst the fusalage, and then leave it for a day and
come back to it.  Then tell us what kind of shape the rubber strands
are in.

Similarly, I could mention the instructions which come with any of the spring
action German air-rifles we've all seen:  "Do not ever leave the weapon in
a cocked state;  that will weaken the spring."

Any archer knows that you do not ever leave a bow strung;  this was 
particularly true of the central Asian composite bows, which are held
against their natural bent by stringing.  Turko/Mongol bows, by the way,
are of wood, animal horn, sinew etc.  The same stuff you're claiming
would do such a wonderful job of holding the 300,000+ ft-lbs of torque
of a sauropod's neck, held vertically in gravity assumed to be as we
experience it, day after day after day for the entire 100+ year lifespan
of such a creature.

There is one other minor problem I might mention which a sauropod would
encounter were he to hold his heck out horizontally, as scientists are now
claiming they must have.  He'd starve.  The good leaves are all above the 
20' - 30' level.

And one final note:  a diplodocid would likely have more of a problem
with this neck torque business than a brachiosaur might.



-- 
Ted Holden
HTE

Newsgroups: talk.origins