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Re: Speedy tyrannosaurs



martz@holly.ColoState.EDU (Jeffrey Martz) writes:

>     Also, although Horner beleives T.rex was a scavenger, I don't think 
>he extends this to mean it was slow moving or sluggish.

I just re-read Horner's, "The Complete T.rex" and you are right
about this.  Horner agrees with Jim Farlow's estimates of T. rex
speed of "twenty-five miles an hour, maybe even thirty-five miles
an hour", but that anything faster is "highly unlikely".

What I have a problem with are scavenger theories based on
obvious errors in analysis or gross misinterpretation of data.
For example, there are people who believe that T.rex *had* to be a
scavenger because it was so sluggish it couldn't possibly catch
anything.  I am not joking:

       "... _Tyrannosaurus_ was incapable of taking large strides.
        In fact its stride was not much longer that the length
        of its foot.  This proves that _Tyrannosaurus_ was a very
        slow moving dinosaur and not able to walk at much more than
        5 kph (3 mph), less than the speed of a man walking."

                        Halstead, L., Dinosaurs, Sterling Publishing Co., 1981
        
This from an eminent scientist at the Univ. of Reading.  By looking
at an actual T.rex skeleton, any six year-old could see the error 
in the above analysis.  A (properly articulated) T.rex skeleton just
screams out for speed.  T.rex had an exceptionally large area on
the thigh bones for muscle attachment, allowing for the powerful
muscles needed to propel it at high speeds.  (Hence, I believe that 
life reconstructions showing thin legs are incorrect, such as the one
on the cover of "The Complete T.rex"; the thighs and calves should
powerfully muscled, as in the Battat model).

If it is true that modern elephants have been clocked at 40 mph,
I have no trouble believing that T. rex could exceed that, understanding
that we are talking about short bursts.  Still, the top speed will
depend on the actual weight which is still somewhat uncertain.  I offer
the follow estimates depending on the weight of an adult T.rex:

        Weight          Top Speed
        ------          ---------
        4 tons          45 mph
        6 tons          35 mph
        8 tons          25 mph

Note that a T.rex running even at 25 mph would be an awesome
sight to behold.  It would have _no_ trouble overtaking (and presumably
gulping down) a Carl Lewis in a 100 meter sprint.

More on the scavenger theories later...

-----------
Achut Reddy                     So many fossils... so little time!
achut@sun.com