Re: T. rex mechanix

[Randy King <randyk@ims.com>]

At 09:42 PM 3/21/98 -0500, you wrote:
>It almost seems like the more I think about the physics of being a rex, the
>less I understand how this animal worked.  Here are some of the things I am
>currently pondering.
>
>Locomotion/maneuverability:  Polar moment of inertia.  
>Anyone who has ever tried to make a turn with a 20 foot ladder on his/her
>shoulder can understand the problem here, except the rex body got up to
>double that length and had, quite literally, tons of momentum.  It would
>have taken a while to get that body pivoting, and nearly the same time and
>energy would have been required to stop it pivoting.  While striding, most
>of the time only one foot would have been in contact with the ground, so all
>turning torque would have had to have been transmitted to the ground through
>a single contact patch that was, what, thirty-something inches across?  The
>rex could have exerted torque more effectively during the time both feet
>were in contact with the ground, but while striding, this would have been a
>very brief interval.
>
>So, was there something else the rex could have done to pivot that body, or
>are we forced to conclude that its lifestyle simply did not require quick
turns?
>

As usual, I'm several days behind, so if this isn't already stated somehow...

Turning isn't always this simple.  By leaning into a turn, you can
take some of the torque off of the foot.  The tail can also be used to
control the torque.  

Of course, there are two problems with these.  If the tail is rigid, it will
be more of a detriment than an asset.  Second, leaning into turns isn't
something a predator can do suddenly, and for a prey, it telegraphs its
moves.

Could Tyrannosaurus have been more akin to a cheetah in its chase?  Could it
have sprinted very fast in pretty much a straight line only, only to consume
all its energy in a short time?