Re: Theropod stance balance

[Martin Baeker <martin.baeker@tu-bs.de>]

> As a biped, I'm sceptical of the "don't fall" strategy
> for (large) bipeds.  But you might be right, of
> course. Good thing they had no beer. 

Some time ago, I did some simple calculation (at that time to understand 
why small animals need faster metabolism than large ones) concerning 
stumbling. Here is what I wrote back then:

"If you are not running on very smooth
ground, you will have to adjust your movements to the stumbling stones you
encounter, otherwise you will frequently land on your nose. Now the time
you have to recover from stumbling or to adjust to uneven ground, is
obviously proportional to the time you have until you belly hits
the ground, i.e. until your center of mass has fallen a certain distance.
This time scales like 

t ~ sqrt(l/g)"

with l being some measure of your length and g earth gravity's 
acceleration. 

So if a human has about half a second to adjust his or her steps to uneven 
ground, a T rex (with perhaps three to four times the leg length) 
will have almost a full second to react, all other things being equal 
(which they are not, I know). So although the injuries from falling may be 
worse for a T rex, it will be easier for it to avoid them (unless 
metabolic rate decreases faster than the time to recover increases).

Cheers,

Martin.



                   Priv.-Doz. Dr. Martin BÃker
                   Institut fÃr Werkstoffe
                   Langer Kamp 8
                   38106 Braunschweig
                   Germany
                   Tel.: 00-49-531-391-3073                      
                   Fax   00-49-531-391-3058
                   e-mail <martin.baeker@tu-bs.de>