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Re: New Tyrannosaurus paper



Demetrios Vital (vita0015@umn.edu) wrote:

<It seems to me that the mechanics of a biped running and falling are
different form a quadruped running and falling.  And by "biped" I don't
mean humans, because we're just very clumsy bipeds.>

  Humans also have the property of having a short moment for the femoral
and cnemial extensors, and so forth, and are especially adapted to
_striding_ and variable walking, than _running_. This makes them only
comparable to variable bipedal running dynamics. And Hutchinson and
Garcia's math apply and accurately predict to, within a margin of error,
clocked human speed. Go figure.

  However, yes, quadrupeds have different effects when running and
tumbling than to bipeds, but there are similarities, especially in the
relative gracility of the limbs, center of gravity, and extension of the
body over the ground and stride-length compared to mass moved and center
of gravity that make all the difference.

  Using Nick's (NJPharris@aol.com) bear, a bear will take a fall more
easily than a horse, despite mass, as a result of it's lower center of
mass, shorter stride, sturdier limbs, and relative flexibility compared to
the cursorially adapted horse. Bears are not cursors ... they are quite
graviportal, though they can vary their stance. I've seen footage of bears
taking tumbles and falls after a hard run, and they take it easily, though
exceptions occur. This is because bears can roll from a fall ... horses
cannot without sustaining serious probable damage, relative to limb design.

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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