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Re: Incredibly preliminary size estimate for new T. rex

I wrote...
> >2) this size may represent the upper limit for theropods.

Jonathan Wagner wrote...
> I am very wary of statements
> like #2 above, both because of limited data (we only have so many very large
> theropods from the K to compare), and because of unsubstantiated
> assumptions (e.g. there is an "upper size limit" [logical, but can we
> assume it?], 

    Hence the "MAY"...

> Now, I understand why workers may feel
> compelled to invoke such arguments in the case of sauropods. However, it
> should be noted that every time we think we've pegged the "limit", a new,
> bigger specimen comes around.

     You are right about the crappy sample size, but I don't think it is
an unreasonable idea that a group of animals sharing a similar basic
design living generally similar lifestyles (predation? scavenging?) might
have a size limit beyond which pursuing that lifestyle becomes unfeasable. 
For example, if we suppose that T.rex,  Carcharodontosaurus,
and Giganotosaurus were all predators of extremely large prey (hence the
large size), then perhaps above a certain size this becomes unfeasable.
Just as sauropods MAY represent the maximum possible size an mobile
terrestrial animal can get composed of normal bone and muscle in the
Earth's gravity, PERHAPS the Big Three represent the same for bipedal
predators who can safely chase down, grapple with etc.. thier prey.
     This is just speculation, but active lifestyles get more hazardous
the more massive you get; remember the numbers from Dr. Farlow's
"tripping T.rex" paper.     

LN Jeff