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RE: New Tyrannosaurus paper

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Demetrios M Vital
> Second question: how does one measure the hip height of a T.rex,
> and how on
> earth does one measure the stride of a T. rex?

Hip height for striding vertebrates is most often calculated as "femur
length + tibiotarsus length + metatarsus length".  However, one could also
estimate an "instantaneous hip height" by creating a mount (or virtual
mount), and measure the vertical distance from the center of the acetabulum
to the ground.

As for stride length: see ANY paper or textbook that covers dinosaur
trackways for how these are measured (linear distance from a given footfall
to the next fall of the same foot).  One can "back-calculate" stride length
for an animal of a given height moving at a given speed by modifications of
locomotion equations worked out by Alexander, Farlow, and various others.

> Third question: what does Hutchinson's paper imply for T. rex stamina?  If
> it was just walking, then couldn't T. rex, or any large theropod, go for
> quite a while?

They do not address stamina here.

> Fourth (and last) question: the "Groucho walk" was seen as a way
> for bipeds
> like T. rex to increase their speed without running, so how do ideas like
> this fit in with the new biomechanical work and Hutchinson's paper?
> Thanks,
> Demetrios Vital
> P.S.  How come the T. rex didn't trip when it RAN INTO A FALLEN TREE in
> "Jurassic Park?"

Because it was only a digital image, and so had no mass upon which gravity
could react... :-)

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796