[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Long-necked stegosaur (the reason for long necks?)

Sorry for the immense delay.

----- Original Message -----
From: "don ohmes" <d_ohmes@yahoo.com>
Sent: Monday, March 09, 2009 1:48 PM

--- On Sun, 3/8/09, Jonas Weselake-George <paleo@ncf.ca> wrote:

For adult members of the largest species one can definitely
imagine issues emerging in a variety of situations. A sixty
ton animal would require upwards of twenty tons on each of
the three feet remaining on the ground (and the actual
weight on some of the feet would be higher due to uneven
distribution). The surface area which is in contact with the
ground is alarmingly small.

True, but not as bad as it seems. Most muds are a mix of solids (typically w/ some sand) and fluids. Once a foot is large enough to move the water and, uh, 'oozier' elements aside, yet compress the solids (which are limited in lateral migration distance) what is left below the foot is essentially a column of sand. At this point, the yield stress number rises _sharply_. 

Don't those solids, too, move aside?

In the 'bottom-less' case (a deep pool of uniform fluid): a large animal will 'notice' a given viscosity less than a smaller one. Whereas pancake syrup might shut down a mouse or even a cat, an elephant would barely notice it...

Both of these cases are testable.

Humans swim (not walk, swim) equally fast in water and in syrup. The experiment has been done. The greater drag and the greater thrust cancel each other out.

It would be interesting to try to make estimates regarding
the maximum height of a vertical obstacle that could be
cleared, the maximum length of trench that could be stepped
over and the maximum feasible radius within which a foot
could be placed (without moving the body as well).
Preliminary estimates should be possible for these areas
using only the articulations of the bones (ie. avoiding
potentially dodgy estimates of muscular force and joint
strength).

Seems useful. Probably been done? Don't know, tho... 

Certainly never been done, or we'd know about it.

There's a lot of obvious research that's never been done, simply because there are 1) not enough scientists in the world and 2) not enough hours in a day.

Back to necks; in my view, no animals have ever been better suited for chugging through deep swamps than sauropods, and long necks fit well in such a scenario. 

How so, and how do their small feet and vertical limbs fit that?

I note that few would agree w/ me, at least publicly, 

Insinuating a conspiracy. Yaaay. Always good. Well done! Carry on.

and know of no way to conclusively test this view. It would be interesting to know if sauropod necks show sign of being adapted to resist upward or posteriorly directed pressure,

Well, the cervical ribs and attached tendons should have offered such resistance, though not terribly much. Probably just enough to keep the animal from breaking its neck when it accelerates or moves the neck around.

such as would occur if a sauropod was moving through very deep mud. 

You mean, they were in the mud up to above their shoulders???

Is that even feasible with an animal that's physically incapable of getting that deep into water because it floats like a cork?

And if it is, how could anything move then? The drag would be enormous.

I also see no reason to think that the stegosaur in question was a swamp-dweller, am sorely lacking in time and so turn this thread over to the tender mercies of others, including those who argue that sauropods spent their days galloping through the countryside, necks as straight as flagpoles, vaporizing theropods w/ their tails, while flinging them like ragdolls w/ off of those mighty necks and avoiding mud like the plague. If there are any of those guys left...

And why do they seem to all be guys, I wonder? 

Well, duh!!!

Because women were kept out of science to a large degree in previous generations. In my generation, they make up a bit over 50 % of the total, as you couldn't have helped notice if you'd been near a university any time recently. So, just wait.

Also, maybe you should ask Kristina Curry Rogers and Catherine Forster about what they think about this matter. Remember, they described *Rapetosaurus*, without a male coauthor...

BTW, sauropods were clearly not capable of galloping. Or probably running in general.