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Re: Tyrannosaurus was not a fast runner



Just to clarify my various posts about this paper. Firstly, I have not
read the paper itself, therefore am in no position to comment on it
(I've only read the on-line version at
http://tam.cornell.edu/students/garcia/.trex_www/naturepaper.html )

(That said, he continues...)

My previous posts were not arguements against the idea of a slower
T.rex, or criticisms against the paper. They were merely meant to point
out that the paper (if I understand correctly) does not say that T.rex
couldn't run or move quickly (two different things). In fact, the
website mentioned above states as its first line: "Tyrannosaurus rex
PROBABLY could not run fast, scientists say" (emphasis mine).

I was trying to make the point that this is not a direct study of
Tyrannosaur musculature. It is a theoretical mathematical model, based
on and tested against LIVING animals, that predicts that T.rex lacked
sufficient muscle mass to move quickly (by quickly, I'm refering to the
Bakker-esque "guestimates" of around 40 MPH). I myself have used 3-D
computer models to create hypotheses in archaeological circumstances.
Here's a quote from my Masters thesis:

"It must be borne in mind that the analysis of the site depended heavily
on the terrain model and not the site itself. The TIN generated from the
site data is only an approximation of the site at best. Although the
number of sample points was high (around 13,000) the density of points
varied across the site. In areas of high artefact concentration the
resolution of the model was quite detailed. In other areas where there
were few artefacts the resolution of the TIN was extremely coarse. If
the contents of an archaeological site are merely a sample of the
original due to the action of formation processes then this DTM was a
sample of a sample, with additional uncertainties regarding the accuracy
and precision of measurement. To treat the results of analysis based on
the DTM as if they were based on the site itself would be misleading."

Computer models are not the be-all and end-all of science. This thread
has prevoked some rather passionate responses, as if the paper stated
that "It is known for certainty that tyrannosaurs could not run or move
quickly. Period". Of course, it doesn't say this at all, not even
remotely.

There is nothing alive today that is anything like a tyrannosaur. To
quote from the website mentioned above:
"Finding an answer was tricky, as the researchers were studying
something they couldn't observe directly. 'We're looking at extinct
animals, which we know very little about, and we're trying to understand
their locomotion, which we have almost no evidence of directly' "

Who knows what sort of special adaptations tyrannosaurs may have had to
allow them to go about their business? I for one am astounded that such
a large creature could have been a biped at all, yet clearly it was.
Please keep in mind that a hypothesis is not an absolute truth. This is
exactly the sort of well thought out and executed research that can only
further dinosaur science. If someone comes up with an equally plausible
model that says that tyrannosaurs could run at 40 MPH, then it also has
to be considered. So long as the research is based on sound principles
and good data, that is.

Personally, I suspect that 30-40 KPH (18-24 MPH) would be a decent top
speed for T.rex. This is also supported by the website stated above. Who
needs a suspended phase when you've got such long legs, and if you don't
rely on cheetah-like speeds to catch extremely fast prey?

In the interests of shameless self-promotional, I've just completed an
animation showing the walking style of T.rex, based on the recent
Allosaurus biomechanical studies. It can be seen at:
http://www.geocities.com/dannsdinosaurs/trexwalk.gif
Not a suspended phase to be seen... :)

-- 
________________________________________________________________

Dann Pigdon                   Australian Dinosaurs:
GIS Archaeologist           http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
________________________________________________________________