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Re: Ceratopsian mass estimates

On Wed, 20 Apr 2005 21:47:18 -0400 (EDT) GSP1954@aol.com writes:
> A shown by the original data sample in the Anderson et al 85 paper 
> the 
> variation of mass in living animals at a given proximal limb 
> circumferance varies by 
> a factor of two.

Has anyone ever weighed the fossil bones of complete (or nearly complete)
Triceratops and T. rex skeletons?  Subtracting the weight added by
permineralization, the result would be "hard data" (factual data, rather
than interpretable data).  Why bother doing this?  See below.

> So all such mass estimates [using circumference of the limb data]
> should show a plus or minus
 > variable of 50%.

My point being, that if one estimates whole-body mass using circumference
data, is it possible that the low-end of a +/- 50% error range may
overlap with the weight of the bones, alone?  (Answer: yes).   If so,
then the weight of the bones (corrected for permineralization) would
provide the worker with a pretty good "reality check" on their results. 
(In geology, we call such a method "ground truth", meaning we compare the
model with the reality, which is directly observable on the ground). 
Truth checks also work in biology.  An animal cannot weigh equal to or
less than the weight of its bones (Paris Hilton being a possible
exception to that rule).

> there is no way they [tyrannosaurs] weighed much more than my
> mass estimates, which are based on volumetric
> models rather than my life drawings. 

What is the error range for your volumetric modeling method in the
estimation of body mass?