From: news@fedfil.UUCP (news)
Newsgroups: talk.origins
Subject: Re: Friesen on elastics and sauropod necks
Date: 2 Oct 92 04:01:57 GMT
Organization: HTE

In article <1150@tdat.teradata.COM>, swf@teradata.com (Stanley Friesen) writes:
*In article <40@fedfil.UUCP> news@fedfil.UUCP (news) writes:
*|[Me]
*|| 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.

*On what evidence do you base this conclusion?

Several varieties of evidence:

1.  We no longer have such creatures, and there must be a reason for that.
    If such sizes worked for sauropods, and if nothing has changed vis a
    vis circumstances which might allow for such sizes, then in all the
    intervening time, something, at least one life form, should have
    RE-evolved into such sizes.  This is, of course, assuming the usual
    multi-million-year time frames given out in schools for dinosaurs.
    In reality, of course, these time frames are wrong.

2.  The only creature with a neck even remotely similar to a sauropod's in
    our world is the giraffe, and he holds his neck up for two very good 
    reasons:  to lessen the torque stress, and to get at high leaves.  The
    strength of these two motives would have been vastly greater for a
    sauropod.

3.  Simple calculations, as I have noted, show an impossible strength
    requirement for a sauropod to hold his head out vertically in our
    world, perceived gravity being what it is now.


*|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.
*
*And *I* repeat, they have concluded that *some* (not all) sauropods held
*their necks out horizontally because that is how the bleeping bones *fit*
*together.  Brachiosaurus is still modeled with a *vertical* neck, because
*that is how *its* bones fit together.

Brachiosaurus would have no less of a problem getting blood to his brain
than any other sauropod, given our perceived gravity.  The facts regarding
this, as put out by McGowan and others do not respect persons.  Brachiosaur
is only being modeled with his neck vertical by people who either have not
read or do not believe in the recent literature.

In reality, of course, brachiosaur HAD to hold his head up to get at the
leaves he fed on.  Getting blood to his brain was no problem due to the
attenuated gravity of the antique world.

*You are *still* getting diplodocids and brachiosaurids mixed up!

You're the one mixed up.  The height requirements for the two kinds of
saurs (getting blood to a vertically held head) would be entirely
similar.  ANd, if the heart needed to do this would not fit in a
brachiosaur, it certainly wouldn't fit in the smaller diplodocus.
*
*|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.
*
*Treated as a rigid bar, with a single lever point.
*Treated as a flexible chord, with a distributed load support, the
*results are quite different.

Even a suspension bridge has a center of gravity.
*
*|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.
*
*Rubber bands are *not* living tissue.  Living tissue has this nice little
*property called self-repair.  It is only after death that ligaments undergo
*degradation.


Death from the kind of stress you're claiming these creatures took for
granted would come within a few days at most.  There'd be no time for self
repair.


*|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.
*
*The leaf level depends on the type of vegetation.   Since the best
*reconstruction of the Morrison environment are of a rather dry, seasonal
*environment, with tall trees restricted to water courses, I think that
*you are probably wrong here.  (The envoronment was dry enough to have
*desert style dried lake beds - playas).

Again, reread what McGowan says about the lives of elephants.  They spend
most of their waking hours eating;  McGowan says it is not clear to him
how anything could eat enough to get any bigger than elephants.  

Digestive efficiency has to be another sort of a square/cube problem in 
that it has to be related in some way to surface area of intestines, 
which will go up as a square.  The digestive efficiency of sauropods was
not likely greater than that of elephants.  

If elephants require huge amounts of lush vegetation, than sauropods were
not going to deserts or environments devoid of tall trees.  The long necks 
figure to have been an adaptation to eating leaves precisely from tall
trees.



-- 
Ted Holden
HTE

Newsgroups: talk.origins