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Re: Tyrannosaurus arms

Sam j hogan wrote:

> Whatever happened to the idea that Tyrannosurus used its arms to
> lever itself up from a resting position?  Not that they could not
> also have been used to protect itself from a fall; after all in an
> emergency, you use what's available.  Extending the arms during a
> fall is done because it helps lengthen the impact time[.]

     According to p. 116 of "The Complete T. rex" (admittedly not much of a
source), T.'s arms were estimated to be able to pull (because of the
estimated bicep muscle size) about 400 lbs each.  That makes sense as a
predator, because you want to be able to grab prey, hold on and pull it
towards your mouth.
     That doesn't address the _pushing_ ability of the arms, though.  Let's
arbitrarily say the pushing ability was about 200 lbs each; that's 400 lbs
pushing ability.  (Has anyone gone through the exercise of figuring how
much a _T. rex_'s head would weigh in life?)  Doubtless this animal used
its arms to at least balance while it got up, but because of the arms'
relatively short length, the legs would have do all the work.
     Which brings up the problem of using arms to break a fall.  The
problems of a falling _T. rex_ have already been covered here in
cyberspace, but as for the arms' usefulness, try this experiment:  Hold
your arms flat against your sides, bent at the elbow so that your forearms
stick straight out in front of you.  Now fall flat on your face.
     Did your arms help break your fall?  Well, sort of!

[ Remember, ladies and gentleman, the people you are watching here are
  trained professionals.  *Don't* try this at home :-) -- MR ] 

T.A. Curtis
13980 Lyons Valley Road
Jamul, CA   91935-2024