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New Tyrannosaurus paper

Tom Holtz wrote:

>Also, size matters, and there is a (biophysiological) world of
>difference between 500 kg and 5000 kg, as we will all be shortly
>reminded later today (he said once again, cryptically, although this
>being Wednesday I think people might be suspicious... :-).

Cryptic?  I just think it's in your Nature...  :-)

Anyway, nestled among the articles on Jupiter in today's _Nature_...

JOHN R. HUTCHINSON and MARIANO GARCIA (2002).  _Tyrannosaurus_ was not a
fast runner.  Nature 415: 1018 - 1021 

Abstract: The fastest gait and speed of the largest theropod (carnivorous)
dinosaurs, such as Tyrannosaurus, is controversial. Some studies contend
that Tyrannosaurus was limited to walking, or at best an 11 m s-1 top speed,
whereas others argue for at least 20 m s-1 running speeds. We demonstrate a
method of gauging running ability by estimating the minimum mass of extensor
(supportive) muscle needed for fast running. The model's predictions are
validated for living alligators and chickens. Applying the method to small
dinosaurs corroborates other studies by showing that they could have been
competent runners. However, models show that in order to run quickly, an
adult Tyrannosaurus would have needed an unreasonably large mass of extensor
muscle, even with generous assumptions. Therefore, it is doubtful that
Tyrannosaurus and other huge dinosaurs ( 6,000 kg) were capable runners or
could reach high speeds.



Timothy J. Williams 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 3163