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Re: Sauropods vs. Gravity



> Hello all! I have a certain topic that I would like to address. One thing
I have been interested in for a while is the problem large terrestrial
animals have in our present gravity on Earth. There seems to be a certain
restriction on size these days, and I wonder why.

Some say when a terrestrial quadrupedal animal has 140 tonnes its legs must
be so thick that they touch, therefore heavier ones are impossible. Who
knows... the archives are _full_ of discussions of that.

> I wonder where along the timeline the Earth's gravitational pull weakened,
if it infact did that.

IT DID NOT. No way. Had the gravitational constant fluctuated, the solar
system would have flown apart immediately, if not even all galaxies. I love
such cases: OUR VERY EXISTENCE proves that this was not the case. Sorry for
shouting. Consider this case closed forever. :-)

> I have been doing some research concerning the body mass of sauropods

Check the archives for tons more! :-)

> If you compare sauropod muscle filaments to that of a human's, you would
find (according to the above reading) that they are pretty much the same.
But as an animal gets larger, the weight goes up in proportion to the cube
of the increase in dimension, since weight is proportionate to volume, of
course. My question is how in the world would a huge sauropod even be able
to breath, let alone function in a world with our gravity?

Well, then, first calculate _how big exactly_ a "huge" sauropod is. If it
has over 140 tonnes then don't worry :-)

> Take the issue of their necks. Sauropods like the giant brachiosaurs (i.e.
ultrasaurus) and seismosaurus had necks 40 to 60 feet long weighing 25,000
to 40,000 lbs.

<tip, tip> Over 11.3 to 18 tonnes? I doubt the entire animals were much
heavier. An entire *Diplodocus* is commonly estimated at 10.6 t. Not to
forget that sauropod necks contained more air than bone.

> One might say that the sauropod's suspension-like skeleton worked in a way
that would support this.

Again, check the archives for lots of discussions about sauropod neck
posture... :-)

> Wouldn't it actually arch DOWNWARD if held out horizontally?

Diplodocid necks indeed arched downward. :-)

> According to Peter Dodson (Lifestyles of the Huge and Famous), "...the
vetebral spines at the base of the sauropod neck were weak and low

Those of *Brachiosaurus* and *Giraffatitan*, for example, are still unknown.

> and did not provide leverage for the muscles required to pump blood to the
brain, thirty or more feet in the air, would have placed extraordinary
demands on the heart and would have seemingly placed the animal at severe
risk of a stroke, an aneurysm, or some other circulatory disaster."

Well then maybe the heart did grow to 1 t in weight. Numbers please.