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Re: DINOSAUR digest 2042



More replies here:


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The current conversation surrounding the Hutchinson and Garcia paper
has left me wondering what information is available regarding the
various aspects of terrestrial locomotion other than top speed. 
Presumably, most (if not all) of the papers regarding the modelling
running speeds, including the Hutchinson and Garcia paper, are only
interested in top sustained speed.  I am not anything remotely
resembling an expert on biomechanics, so I thought I might ask those
of you out there who are:

What information/models are available to examine things like
accleration, turning, etc.?  

Thanks in advance,
--Mike Habib
habib@virginia.edu
 ========

Great questions.  We still know very little about the actual top speeds 
of many animals, as we found out with our elephant research project.  
It is hard to accurately measure these things.  But turning and 
acceleration are even worse known.  There are precious little data and 
we really need a lot of work done on it.  Work by Jindrich and Full on 
insects, a few human locomotion studies (including Carrier et al. in 
recent Journal of Experimental Biology, with infamous "dinosuit" 
paper), and some others are all that exist for terrestrial animals.  
Lots of attention is starting to focus on this problem, though.  It is 
a very complex dynamic problem compared to steady-state locomotion!

========

As the discussion is dying down, and I need to devote more time to 
work, and there are new JVP papers and a new dino paper in Nature 
coming out this week (you'll all love this one!!), among others, I'll 
spend less time hogging list bandwidth.  A few final comments:

     The most important point that has been muddled in the coverage of 
our Tyrannosaurus running paper is that we do not explicitly say that 
Tyrannosaurus could not run.  In a more crouched pose, it does not make 
sense in our model and I doubt it would work.  But with a more columnar 
limb orientation, I cannot rule out some form of slower running; it is 
quite possible. We will investigate this with some more realistic 
models.  There are lots of complex tradeoffs in the model between size, 
speed, and limb orientation, and too many unknowns to rule out lower 
speeds of 10-25mph, which I agree are still fairly fast by human 
standards (not cheetah standards though!).  I emphasized this in the 
webpage and in talking with reporters, but it's a hard sell and didn't 
always come through clearly.
What I do feel that we rule out, not conclusively for all eternity but 
in the context of known data, is 45mph top speeds.  Not only would a 
tyrannosaur become critically unstable at such speeds, and maybe fall 
if it tried to reach them, it just wouldn't be able to produce the 
necessary moments to do it in the first place.