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RE: Evolution of tyrannosauroid bite power

> Tom Holtz wrote on Thu, 20 Dec 2007 08:25:19 -0500
>>Well, of course, and I think everyone working on this would agree exactly
>>with that scenario.
>>But a biomechanical analysis must needs focus on one particular part of
>> the
>>organism, and later be integrated into other comparable systems.
> That is the traditional approach, but methods for analyzing the motion of
> complex (i.e., multi-part) mechanical *systems* are being developed that
> show a lot of promise for analyzing biomechanical systems. The
> methodological problem in analyzing each part of an animal separately is
> that the parts are not independent of one another.  Analyzing them as a
> complex biomechanical system with multiple dependent parts is an effort to
> get away from that problem. For an example from mechanics, see Hong and
> Cipra's 2003 paper illustrating a method to analyze the motion of complex
> cable-pulley systems, which can be found on-line at
> http://www.me.vt.edu/romela/RoMeLa/Publications_files/JMD2003_CablePulley.pdf.
> It's probably not the best example, but it's useful for illustrating the
> distinction I was trying to make. It seems to me that the relationship
> between arm size and bite power, or arm strength and hip strength, offer
> some real potential for using this type of systems analysis.

But that is a separate question (or rather, a second level) from the
evolution of tyrannosauroid bite power.

One level is the changes in bite power over time.

A second level is how that change might be integrated into the organism as
a whole.

Only testing the second fails to actually capture the information in the

In other words, no single study can sum up the system. You need to look at
different levels.

And let me throw in that the neck muscles (including the shoulder muscles)
really have to get incorporated into it.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661

Faculty Director, Earth, Life & Time Program, College Park Scholars
Fax: 301-405-0796

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA