Re: PARTICULAR sauropods aquatic?

[Dinogeorge@aol.com]

In a message dated 9/2/99 11:29:27 AM EST, mbonnan@hotmail.com writes:

<< However, completely submerged sauropods would seem to be impossible 
 based on the laws of physics as we understand them. >>

There is at least one sauropod trackway (found by Bird? can't recall right 
now) that includes only forefoot impressions and could only be produced by a 
sauropod walking in fairly deep water with its hindquarters floating off the 
substrate.

Considering how pneumaticized sauropod skeletons were, it might indeed have 
been impossible for them to submerge completely, since their overall density 
would have been significantly less than that of water. It is easy to picture 
sauropods swimming across rivers and lakes with much of their backs out of 
the water, as illustrated in a number of children's dinosaur books over the 
years. The famous Burian picture of _Brachiosaurus_ entirely submerged with 
just its head showing above water (which I loved when I first saw it), 
however, probably couldn't have happened. _Brachiosaurus_ had particularly 
extensive skeletal pneumaticization and was probably particularly afflicted 
with the low-density problem.

Anyway, the low density of sauropods would have worked to keep the lungs 
quite close to the surface when they were swimming, so that having to inhale 
against the pressure of several meters of water would not have been a 
problem: They simply couldn't submerge that deep. (Unless you can imagine a 
giant hand pushing them underwater from above...)