[no subject]

[jrhutch@socrates.Berkeley.EDU]

=========
And my sources for the 9 mph figure are members of this DML, whose emails,
in which the figure is reported, should be in the archives.  I believed
those reports, and thus cited that number.  Are those reports wrong?  You
can find what I'm referring to here:
http://www.cmnh.org/fun/dinosaur-archive/2001May/msg00354.html
Check the secod paragraph down.  Or, I'll just cite it here:

HP Steve Brusatte wrote (linked to above):
"John HutchiNson (I'm a
journalist that can spell) opened the day with an intriguing talk on
dinosaur
locomotion.  Basically, he recounted his disproving of the hypothesis that
Tyrannosaurus could run at speeds of 20 miles an hour (which has been said
in
the literature numerous times).  Instead, he said that Tyrannosaurus
likelycouldn't run at all (meaning there was no aerial phase to its gait),
and
its
top speeds were likely in the 9 mph range."

Either way, I will not cite that report again.  I hope I have not conveyed
any misinformation, or said anything wrong. I respect and have learned
from
your comments above concerning the difficulty in guaging top speed in
extant and extinct animals.  Thank you for correcting me!

Hoping everything is cool, Demetrios Vital
==========

No problemo; I just wanted to clear the air on what my research suggests
and not let any misconceptions propagate.  I think the post from the
Armour symposium was slightly inaccurate.  One slide I showed used the
Froude number (velocity-squared divided by [hip height times 9.81
m/s^2]) as a theoretical estimate of when a Tyrannosaurus would have had
to switch from a walk (pendulum-like mechanics) to a run (spring-mass
mechanics and probably an aerial phase). This would be at a Froude # of 1
at most, theoretically, although the Fr theory has some assumptions that
don't work so well for running. The speed at which Fr=1 would have been
around 5-6 m/s in an adult Trex.  So I was using it more as a point of
reference than a solid estimate of maximum speed.  The higher speeds that
I was saying were unlikely from a biomechanical viewpoint were on the
order of Fr=16; around 20 m/s (~45 mph), not 20mph.

Best wishes, John