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Re: Diplodocus: Return to the Swamps????
>> You seem to miss the reality of
> > a swamp; sooner or later you _sink in_ no matter how
> 'spready' your feet are. At which point,
> > 'spready' feet are a serious _disadvantage_. Swamps
> often have sharp sticks, logs, even rocks
> > that can function as impalers or entanglers. If the
> area has a bottom you can reach, you WANT
> > compact feet that slide easily to it, and then
> _retract_ easily.
> Theropod feet spread on the way down, but fold up into a
> nice compact narrow shape on the way
> back up. The spread foot makes it more difficult to sink
> into the mud to begin with (and less mass
> doesn't hurt either). The more compact retracting shape of
> the foot means it's easier to extract it
> from the mud than it was to push it in.
Spread toes are vulnerable to injury in deep mud when you weigh several tons.
"...sharp sticks, logs,..."
> > And less power...
> Mass isn't necessarily a good measure of power. In fact,
> I'd go as far to suggest that theropods
> had a greater proportion of locamotive muscle mass than
> sauropods had. A biped needs leg
> muscles to actively keep it upright. A quadruped just has
> to lock up its leg joints when its not
> moving, and it turns into a passive table.
That is relative power. Mice have very high relative power, but cannot break
free of a sticky trap... absolute power is what is needed in mud. Sauropods had
the mass AND the leverage.
> > ...When you are up to butt in mud, you have no
> worries about that...
> I'm not envisaging regularly moving through crotch-deep
> mud, since no sane animal would do that
> very often.
Nothing insane about being theropod-free when you have a long skinny neck and
tons of tasty meat. Not to mention being thermally stable. Takes the weight off
achy feet, too. Reach up, nip a few leaves, go back to sleep...
Big old mud-bug could have a good life.
> Rather, I'm suggesting that large theropods did
> better than sauropods on slippery
> ground with no more than ankle-deep mud - something most
> dinosaurs would have encountered at
> some point (as evidenced by trackways).
Certainly there was theropod-friendly terrain, and sauropod-friendly terrain.
But what you describe is not a swamp by any definition I know of. Swamps, btw,
don't preserve tracks per se, barring possible underprints...