Why were _Tyrannosaurus rex_ forelimbs so massively muscled?

[Larry Dunn <majestic_cheese@yahoo.com>]

Someone please help me to understand why
_Tyrannosaurus rex_ forelimbs are considered to have
been so heavily muscled.  I understand how Horner's
people came to the conclusion, but I don't understand
the *comparative* nature of the observation.  

Said differently, and certainly more clearly, were
their muscles in fact comparatively more massive than
the arm muscles of other theropods?  (I hope my
question is clear.  No need to reiterate Horner's
observations.)

And, if so, why would this be so if they were so
evidently useless?  (I've heard some of the theories
of usage for the forelimbs, but they seem, frankly,
ludicrous in the face of the restorations done by
Horner's people and others.)

An associated question: many life restorations show 
longer skinnier forelimbs.  Is the jury still out on
Horner's restoration?  (I know I've asked this before,
but was wondering if attitudes had changed since
then.)


=====
Larry

"You look like an Albanian fellow whose owl has just died."

http://members.tripod.com/~megalania/index.html
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