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Re: Tyrannosaurus was not a fat boy or girl



GSP: Briefly - systematically iterating a physical model (as distinct
to simply 'adding as much plasticine as seems anatomically possible')
to account for uncertainties in proportions and overall size is
difficult to do without introducing small errors in scaling (if
explicit scaling is actually used), the effect of which will be
magnified the smaller the model is, unless (or even if, at very small
scales) CNC tools are being used. Computer models make things
considerably simpler and more controllable. If one wishes to observe
the effects that enlarging the tail has on estimated mass and CoM, one
simply needs to tap in an exact scaling exponent and re-run the
analysis. As we discussed in the paper, it is very difficult to remove
the effects of subjectivity when reconstructing morphology, but
computerised modelling will always have the advantage of an
immediately accessible and quantifiable relationship to the fossil
material, to a degree not present in all but the most sophisticated
physical modelling techniques.

Additionally, the use of sub-millimetre accurate scanning machines
(the accuracy of which vs manual measurement I'm not sure requires a
comment) to generate the ridiculously high-fidelity clouds of
measurements that these models are based upon seems, to me at least,
to be a rather obvious improvement from basing a scaled down model on
manual measurements or on manually produced scale-models. This
technology exists, is practical, is affordable, and can generate
literally thousands of measurements in the time it takes to write this
paragraph. Why not embrace it?

On 23 October 2011 14:48, Jay <jayp.nair@yahoo.com> wrote:
>
>
> Would be remotely helpful for readers if you posted the link to the comment 
> on the Hutchinson et al paper, since you mention it here, Greg.
>
> http://www.plosone.org/article/fetchArticleComments.action?annotationId=info%3Adoi%2F10.1371%2Fannotation%2Fb76d947b-ec96-4954-84fa-31a558c17542&articleURI=info%3Adoi%2F10.1371%2Fjournal.pone.0026037
>
>
>
> ________________________________
> From: "GSP1954@aol.com" <GSP1954@aol.com>
> To: dinosaur@usc.edu
> Sent: Sunday, 23 October 2011 8:25 AM
> Subject: Tyrannosaurus was not a fat boy or girl
>
> I've placed a comment with the Hutchinson et al. PLoS One paper on
> Tyrannosaurus masses.
>
> Enjoy.
>
> It is becoming apparent that the uncertainties is restoring the power
> dynamics of extinct animals are so extensive that it is not possible to 
> calculate
> whether or not adult Tyrannosaurus were slower or as fast than the
> obviously fast juveniles. If someone eventually comes up with power 
> calculations
> estimating that an adult Tyrannosaurus could run 30-35 mph I will be happy but
> not sure how it is more reliable than those estimating only 20-25 mph. We
> are going to have to wait until time machines are available. I shall get to
> work on that.
>
> Also do not quite get the plot in Fig 6 in the Hutchinson et al. paper. It
> seems to show 10 yr old Tyrannosaurus not weighing anything. Odd.
>
> GSPaul</HTML>
>