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Re: rearing up (long)



Ron Orenstein wrote:

<This is going to sound like an extraordinarily silly
question, but here goes.>

  Silly? On this [Cope] list? Oh, perish the [Cope]
thought! If anyone [Cope] thought it [Cope] was funny,
a certain biologist [Cope] would be turning in his
[Cope] grave. Without his [Cope] head, of course
[Cope].

  Ah, coptharsis feels so good, and I'm getting
carried away.... :)

<I am not sure I quite understand why rearing would
cause additional blood-pressure problems (barring the
increase in activity rate). As the heart is in the
anterior half of the body, rearing does not
necessarily raise the head higher relative to the
heart, because the heart is elevated too. If the
rearing animal then bent its head well forward to
reach branches on the far side of the tree it might
even come level with the heart. If pooling in the
posterior extremities is the problem, surely either
constricting the posterior vessels or using muscle
activity to "pump" the blood back to the anterior end
could solve this problem (this is akin to what diving
whales do). Am I missing something?>

  I'd pictured something you just described, Ron, last
night, in that a sauropod, while rearing, could bend
the neck downward it what would seem to be a far
easier thing to do than to elevate it,
zygapophyses-wise, regardless (and in spite) of what
I've said on this thread the last few days. [It
appears the "painless dislocation" is best confined to
the limbs, rather than the axial skeleton.] This would
at least partially increase or level the
blood-pressure toward the head, and also might solve
diplos "exploding heads." Not so for Brachios, but...

  However, unless the animal would keep the neck so
level to the ground, rearing or not, why rear in the
first place?

  A problem I see in the rearing sauropod is, in fact,
it would decrease the blood-pressure given the
straiter upright neck as the animal went up. The heart
would move higher, but so does the neck, and
exponentially so, towards the head, as distance from
the center of the earth increases. I don't have the
mathematical formula for this, otherwise I'd share it,
but I'm sure somewhere, either one to two years ago,
someone gave a figure for the brachio neck in the
classic, upright style.

===
- Greek proverb: "Knowledge is Inherent;
  Stupidity is Learned." -

Jaime A. Headden

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