Re: Biomechanics

["Matthew Bonnan" <mbonnan@hotmail.com>]

Michael Teuton said:
Also the animal could breathe with most of its body submerged if it had
> enough muscle to push water out of the way by what ever means a sauropod
> breathed.  I believe it would have more than ample power because it was a
> huge animal.
>
> This all relates back to dead space in the airway discussed some time ago.
> Humans are not able to snorkel with too long a line because we are not used
> to adding that much dead space to our air column.  We cannot eliminate CO2
> adequately if there is too much dead space.  Sauropods are or more 
> correctly
> were able to handle it somehow.

Ooo ... careful, careful.  It's not so much the CO2 as the air pressure 
differential that gets we humans.  When you're breathing atmospheric 
pressure oxygen but having your lungs squeezed by several atmospheres of 
pressure, that's where the real problem lies.  A better test of your CO2 
idea would be breathing through a long tube in the SAME atmospheric 
pressure.

Water is very heavy stuff (approx. 8lbs. per gallon!) and every 10 ft or so 
below the surface adds another atmosphere of pressure -- hence the 
pressurized tanks of divers and the bends.  If we momentarily disregard 
pneumatization of sauropod vertebrae (not limb bones which were almost 
completely solid), if you have a nose sucking in air at atmospheric pressure 
but lungs which are, let's say 30 feet below the surface, you may have some 
problems on your hands.

In any case, the bodies and limbs of sauropods are indicative of terrestrial 
animals, rather than ones that are aquatic.  Their bodies are not wide like 
those of hippos and other semi-aquatic denizens, and their feet and long 
pillar-like limbs appear better suited for drier, although not necessarily 
DRY, habitats.  Don't confuse this as saying that no sauropods ventured into 
water!  I just don't think it was their sole niche.

As for the large bodies = large muscles, it's hard to judge the size and 
capacity of the lungs, diaphragmatic muscles (or what have you), and the 
intercostal muscles and the contributions of each to the whole picture.

Keep in mind, too, that the sauropods with the "tallest" necks (i.e., 
Brachiosaurus, Camarasaurus) tend also to be the sauropods with the longest 
and narrowest hands.  One would suspect that if such "tall"-neck sauropods 
were venturing into the water, we should find they had the squatest, 
shortest hands.  Instead, the more horizontal-necked diplodocids have these, 
along with the largest thumb claws and most flexible hind feet.  My vote for 
most likely to enter the water on a regular basis would be the diplodocids, 
rendering most of the nose-above-the-water speculation moot.

It's amazing how far Owen's "Cetiosaurus" (literally whale reptile) 
conception based on the fragmentary sauropod remains has reached into the 
present.  Again, while I do not doubt that sauropods ventured into water on 
occasion or perhaps more regularly, their skeleton seems to suggest a more 
terrestrial lifestyle.

Comments? Criticisms? Suggestions?

Matt Bonnan

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