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Re: Theropod posture-in-motion article



Before critiquing the Carrier et al. study, be sure to read the upcoming paper, especially if you haven't seen the authors give their talk on this at SICB.  Some of these critiques below were addressed by the authors.  Don't trust a couple of short web blurbs about some complex research to provide much accuracy or depth on the authors' work or on colleague's reactions to the work (the ABC story attributes some comments to me about predation on young theropods that I never made; go figure).

Furthermore, the recent comments on morphological details and anatomical dissimilarity miss the point of the study.  The study is not about leg stresses, muscles, or other factors.  It is a biomechanical study of the dynamics of turning, and as far as I know the laws of physics apply equally well to a human in a dinosuit, an ostrich, or an allosaur.  Many locomotor behaviors can be abstracted down to a few physical parameters regardless of anatomical details such as "cursorial specializations," etc.

My comments do not constitute an endorsement of the authors' conclusions, but are merely a cautionary note about the unreliability of internet information on dinosaurs and the scientists who study them.

--John

==========================
Date: Mon, 27 Aug 2001 15:49:59 -0700
From: David Krentz <David.Krentz@disney.com>
To: dannj@alphalink.com.au
Cc: dinosaur@usc.edu
Subject: Re: Theropod posture-in-motion article
Message-ID: <3B8ACE97.D0C5A92C@fa.disney.com>
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Dann Pigdon wrote:
>
> bh480@scn.org wrote:
> >
> > From: Ben Creisler bh480@scn.org
> > In case nobody's mentioned this, a new view of theropod
> > posture and motion is discussed at:
> >
> > http://www.abcnews.go.com/sections/scitech/DailyNews/dinosu
> > it010827.html
> >
> > This topic was also discussed in the on-line news section
> > of Science magazine last week, but you need a subscription
> > to read it.
> >
http://sciencenow.sciencemag.org/cgi/content/full/2001/820/
> > 2
> >
> > Haven't seen the Journal of Experimental Biology yet,
> > though.
>
> To be honest, this research (if it can be called that) seems full of
> holes. How can a human body, no matter how many weights and bits of
> lumber are strapped to it, ever mimic the stresses felt by a theropod?
> You'd have to have major surgery to alter the way the leg muscles attach
> to the pelvis, and to restrict the range of motion of the knees and
> ankles. A human, who has walked in a certain way most of their life,
> straps on some hardware and declares "ooh... this feels weird. They
> mustn't have done it this way" after only a few hours or days. It must
> be so!
>
> Now, if the subjects had radically different skeletal and muscle
> structures, and had lived their entire lives as a one-man-hardware
> store, perhaps then...
>
> --
> ________________________________________________________________
>
> Dann Pigdon Australian Dinosaurs:
> GIS Archaeologist
http://www.geocities.com/dannsdinosaurs
> Melbourne, Australia
http://www.alphalink.com.au/~dannj/
> ________________________________________________________________

This is strange research. What about very minute movements of the
head, neck arms and trunk, not to mention some help from the tail that
could help an allosaur with a turn. It would be interesting to see how
much the trunk and tail could aid in a turn. I cerntainly don't think
that the rest of their anatomy was a stiff as a board, literally.

================================================================
John R Hutchinson
Department of Integrative Biology
University of California                           phone:    (510) 643-2109
Berkeley, CA  94720-3140                        fax:   (510) 642-1822
http://www.ucmp.berkeley.edu/people/jrh/homepage.html
================================================================