Re: Sauropods in wet versus dry environments... a tip of the hatto some past ...

["David Marjanovic" <david.marjanovic@gmx.at>]

> You might be surprised to learn that when something makes a track, the
> substrate grains are not driven closer together but are driven apart. This
is
> because the grains are already maximally closely packed and cannot be
driven
> closer by the action of the foot.

This is true by some but by no means all substrates.

> For example, when you walk on wet sand, you will notice that
> the sand dries momentarily beneath your feet. This happens because the
sand
> grains are moved apart, allowing the water in the immediate vicinity to
> escape into the widened interstices between the grains. In due time the
> grains fall back together and the water is squeezed back out again.

Maybe it's the other way round: you momentarily compress the interstices and
squeeze the water out? Such beach sands (at least those few that I've run
on) are slightly elastic, which I can't explain by your model.