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RE: brief replies




-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
jrhutch@stanford.edu
Sent: Sunday, March 03, 2002 1:55 PM
To: dinosaur@usc.edu
Subject: brief replies

Hi again,
  Just a few comments to catch up on things I haven't replied to yet.  I
may not be able to reply to too many e-mails this week as I am off in
NYC doing research (3D laser-scanning Velociraptor legs for more
musculoskeletal models!).  As has become habit, Tom Holtz (with John
Merck and an entourage of students and teachers) and I just ran into
each other last night at the hotel through freak circumstance; 2nd time
in recent memory.  Small world!<<
Isn't it great when that works out? Sounds like interesting work, I'm
looking forward to your work.

>>Anyway, there isn't too much for me to reply to (phew, life has quieted
down at last!), but Tracy and Mickey mentioned that our Fig 1 is of
Daspletosaurus/Gorgosaurus. We did not assign the drawing to a genus,
and for our purposes it did not matter what genus was used. As you
probably realize, the illustration (which is properly credited, not
"ripped off") is from PDoTW and was just used as background to show the
whole body rather than just a boring stick figure.<<
Doohh, should have read that.
  >>We used the joint angles from that drawing because it is one of the only
reconstructions
of a tyrannosaur hindlimb in midstance that we could find. It is odd
that most artists show one limb (usually right) in late stance and the
other in late swing phase.  We tried some 30 different limb
orientations, only a few of which are shown in the Nature paper (see
simple 2D models in supp info gif image... they are ugly but they are
the real models and may show why we added extra art to figs 1+2).  It
didn't matter too much for our T estimates unless we used fairly
columnar limb orientations that put the trunk CM very close to the knee
joint.<<
Anyway, to me at least, I find it disconcerting that if someone is talking
about a certain animal then it's best to use that animal in your
illustrations. How hard is it to find a drawing? I mean, alls you have to do
is take a skeleton of T. rex, redraw it with the leg in the position that
you want. How hard is that? I can do that in less than 10 minutes (of course
I have been doing this kind of thing for over 10 years so it is easy for
me). So if anyone out there in the paleo world and you need good skeletal
illustrations I'm here for ya. The problem with not using the animal your
talking about in your illustration is others will missinterput that
illustration as to what that animal really looked like.
An example (short of) is when Supersaurus scapula was found and drawings of
it were put in kids books there is a large bulge near the posterior end. I
tried to figure out what that was or where the artist got it. I finally
found out, it was from a quarry map and there is a rock near the posterior
end that the artist mistook for bone. Kind of funny really.

>>My opinion is that it has become untested dogma to assume that these
features evolved specifically for, and were maintained for, high speed
running only. The burden of proof is on people to demonstrate that these
features are useless or unimportant for fast walking or slow running.
They probably are also energy-saving mechanisms that are important for
animals that are on the move a lot.  We need to take a more scientific
look at cursoriality rather than make assumptions without ruling out
alternative hypotheses.  And I think that process of ruling them out
will be very hard.  Computer modeling and more work with living animals
are two approaches that might be productive.<<
I personally have not problem with a slower T. rex, in fact I think all
dinosaurs were slower than others believe (for other reasons then the legs),
it's the movement of the legs that bothers me and I really need to look into
that for my self.

>>Finally, thanks a lot to Luis Rey for the great tyrannosaur-chicken
painting, which has been shown on a lot of websites and news programs
(really great plug on NPR from the host!).  It was a real pleasure to
work with Luis!  I recommend to other scientists that he (and other
illustrators too I'm sure; I've only worked with Luis so far) is a kind
and reliable collaborator.  As you may have guessed, the painting was
done as a potential cover piece for Nature, but we found out that they
don't like humor as much as Science mag does (long story there).<<
I really need to get into color :( Luis is great and has a unique and
wonderful view of the prehistoric world. He has a very colorful view of the
past and he's probably right about that.

OK enough for now, thanks for putting up with me.  :)

--John (no need for formalities like Dr or HP Hutchinson unless you
must; I am not keen on honorifics)


Tracy L. Ford
P. O. Box 1171
Poway Ca  92074