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RE: Re[1] Limb proportions (was RE: Many, many thoughts & responses re: the Hutchinson-Garcia paper)



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> dexter dexter
>
> << Yes. Cats are not built along the same lines as theropods.>>
>
> Kay. I just wanted to show why I did not buy the "longer F/T
> equals slower" thing, compairing two similar sized animals
> (Cheetah, Gazelle) with very different F/T ratios.

Fair enough.

> << Quadrupedal mammals are interesting in that they can flex
> their dorsal column to increase stride length; the master at
> this is, not surprisingly, the cheetah.>>
>
> Okay. If we compaired a _T-Rex_ to an Elephant, my take is
> that the Rex would be faster (e.g superior on nearly every
> aspect; Very different locomotion habits though). So perhaps
> we could wait until Hutchinson explains how it is possible
> for African Elephants to reach 25 mph (11 m/sec-1) before
> buying their study ... Just my thoughs.

One important thing to remember here: elephants do not run (at least by the
old definition; as Hutchinson has pointed out, it will be difficult to test
an elephant on a force plate... :-), they just walk really fast.  John is
actually investigating elephant locomotion.

I concur on your general impressions of _T. rex_ vs the elephants, though.

> << So the T. rex with the 1280 FL is MOR 555. MOR 009 (with
> an 1143 mm FL) is actually closer to the _Acro._ specimens.>>
>
> I was reffering to the NCSM 14345 specimen of _A.atokensis_
> described in Currie's 2000 paper. According to the paper, it
> has a femur of 1277 mm, a tibia of 960 mm and an MTIII of
> 439 mm with phalanges said to be "over half a meter". NOT
> according to the paper, but from what I have read, those
> would be about 53 cm. Question : Why are we leaving out
> phalanges ? In my eyes, they are needed in the "longer
> metasarsals equals faster" thing, since they walk on their toes.

Actually, by "walking on their toes" (i.e., digitigrade stance) we really
mean "metatarsals do not contact the ground except at the
metatarsophalangeal joint".  In fact, in gross observations, fast runners
typically have shorter toes than slow plodders.

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

>