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Re: Muddy feet, or not?

Roger A. Stephenson wrote:

>Since there are so few trackways or track as the case may be, of
>Tyrannosaurids, in the USA can we infer anything from the meager evidence?
>Could it be they didn't like walking on slippery mud, and possible falls,
>(no joke this time)?
>Could it be there was no surprise advantage in being on on a lakeshore in
>the open and weighing 6 tons, and being he most powerful predator around.
>The chase would be futile on the mud flat, unless the Tyrannosaurid got lucky.

I can think of at least two reasons it might have been in T. rex's interests
to venture into mud.  One is in the case of trapped prey.  When a lake dries
up, for example, there is often plenty of fish ripe (phew) for the taking.
The other is to pass through the mud in order to wade out into deeper water.
In four or five feet of water, rex could still have maintained a strong
wading pace as almost all of its bulk would have been above water and it
would only have to overcome the water resistance from about the knees down.
Smaller animals, however, (even ones that were normally faster and more
agile than rex on land) would have had very little weight on their feet with
which to wade, or they might even have had to swim.  In either case, they
would have been comparatively slow and easy targets for a wading rex.
Presumably such animals did cross rivers occasionally, and we think some
animals waded out to island nesting colonies.  And if modern crocs can drive
fish up against land, it is not inconceivable that rex could have done the
reverse and driven small game out into the water.

Tyrannosaurids may indeed have avoided mud, but if so, I suspect it was for
other reasons than that there was no opportunity for food to be found there.