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Re[1] Many, many thoughts & responses re: the Hutchinson-Garcia paper - LONG




> From : "Edels" <edels@email.msn.com>
> Date : 04/03/2002 09:28:06
<< Just adding my 2.5 cents to the roar:

>First, I would love to be able to say that _T. rex_ ran at
>35-40 MPH. HOWEVER, we have NO EVIDENCE that currently
>CONTRADICTS John & Mariano's new findings.
>Second, their web site is very well done. [I do not have
>the paper, and can only go by the web site, the articles,
>and comments on the list here. The physics seems sound.
>(BTW, I have a B.S. in Physics)]. Overall, a job well
> done.
>
> Third, a 5 m/s to 11 m/s range of speed translates into 10
to 25 mph range.
> This actually quite fast for a large animal, especially
one balanced on 2
> legs. Remember that the fastest time for a human is just
over 10 m/s - and
> that's only for 100 meters! As mentioned, even some of
best conditioned
> members of this list might have great difficulty passing 8
m/s (around 18
> MPH). [Note that I, personally, do not qualify as still being
> well-conditioned. :-) ]. So most of us would be _T. rex_
chow!>>

I timed myself at 14 mph. But that's on 70 meters. Guess i'd
be dead too ... And if we were to meet a rex, we'd certainly
not be in a college running track ...

> If we look at how large the femur and illia are in the _T.
rex_, we
> naturally expect that it could move a massive creature
very rapidly. But
> there are limits.
>
> Consider this, however: Of all the large theropods
(_Carcharodontosaurus_,
> _Giganotosaurus_, _Allosaurus_, etc.) _T. rex_ seems to be
the one with the
> MOST massive thighs and hips. This would imply, at least
as far as I can
> see, that _T. rex_ could move faster than those others,
because their legs
> and hip structure would not allow for nearly the same
amount of muscle mass
> (or percentage of those muscles versus total body mass).
True, on an
> absolute flat-out race between the 3 dinos I mentioned
above and _T. rex_,
> _Allosaurus_ MIGHT win because of the lower overall body
mass. _T. rex_
> would come in second. I would be interested to see if
John would analyze
> _Allosaurus_'s speed range as well, to see if my surmise
is correct.>>

That kinda bothers me. There isn't Much of a difference.
T-Rex's ilium is slightly longer than it's femur (About 1.05
ratio) while in _Giganotosaurus_, _Allosaurus_ and
_Acrocanthosaurus_, the ilium is about 0.9-0.95 the lenght
of the femur. Not much of a difference. Also note that their
femurs are longer in relation to the rest of the leg, so
it's a bit unfair. There really isn't much of a difference.

If you ask me, Allosaurus would beat the living crap out of
all those three in a race. Acrocanthosaurus would be tied
with _Allosaurus_, T.Rex would come a conciderable margin
behind and Both _G.carolinii_ & _C.saharicus_ would end up a
few steps behind ...

>
> Concerning some of Dann's points below:
>
> The 9.1 m/s mentioned in Tom's post and Dann's are under
the maximum
> proposed by the Hutchinson-Garcia paper. It remains
possible that this is
> indeed the top-end for the safest, fastest speed by a _T.
rex_, and possibly
> for the Jurassic theropod as well. (This is just over 20
MPH for us
> Americans :-).
>
> As to whether _T. rex_ was an ambush predator, I think
that an ambush would
> be a very good use of those massive legs, surprising the
unwary
> _Edmontosaurus_ (etc.). However, I think we need John to
work on the model
> for 4 legged animals, and crank some of the larger
sauropods through it, and
> present us with a speed comparison chart (Or, maybe some
enterprising grad
> student could finally find a topic in this for his/her
dissertation).>>

I don't think it's proven that a quadruped animal of the
same size has an advantage over a biped animal of same
weight ... Compair an ostrich to another 100 kg 4-legged
critter ...

>
<<> Another use of _T. rex_'s massive legs could be to hold
down his prey, much
> like modern birds of prey do. Jack Horner, in one of his
many statements
> about the poor hunting skills of _T. rex_, said "Maybe he
hid behind a rock
> and jumped out and kicked over a _Triceratops_!". Ha-Ha,
Jack - maybe
> that's exactly what he (_T. rex_) did do! Then, he held
the animal down
> (with those legs), and bit into its back and neck to kill it.
>
> I've also thought that maybe the huge legs on _T. rex_
would make it much
> easier for the animal to raise itself up from a "prone"
position to stand.
> (I put quotes around prone, because I think the animal
couldn't lie down
> completely - probably rested on the pubis, which I think
would have been
> very padded).
>
> I like Currie's idea about the younger rexes doing the
hunting. Of course,
> it is possible that the younger ones did the chasing, and
chased the prey to
> the waiting adult, who provided the coup-de-grace.
>
> Referring to the recently concluded Olympic games, the
current state of the
> art in figure skating is a quadruple spin (Quad Toe-Loop
and Quad Lutz). It
> may come to pass in our lifetimes that someone, somewhere
will be able to
> leap from skates, spin 6 times, and land, safely and
elegantly. {Note that
> NBA players like Kobe Bryant could probably jump high
enough to spin 6 times
> and land safely - but I doubt they could do it on skates -
let alone
> elegantly). I'm sure that someone will be able to
calculate an upper limit
> to how high someone can jump from ice, and how many times
they can spin
> (which is a function of how high they jumped), and still
land relatively
> safely. This is a similar situation with _T. rex_ - there
has to be some
> sort of limit - These are real, physical creatures, and
they are bound by
> the same laws of physics we are.
>
> Just remember, although _T. rex_ is not a speed demon,
it's still a very
> fast animal. And it still is one of the most powerful of
the theropods.
>
> Thanks for listening! :-)
>
> Allan Edels
>
>
> -----Original Message-----
> From: owner-dinosaur@usc.edu
[mailto:owner-dinosaur@usc.edu]On Behalf Of
> Dann Pigdon
> Sent: Friday, March 01, 2002 6:46 PM
> To: dinosaur@usc.edu
> Subject: Re: Many, many thoughts & responses re: the
Hutchinson-Garcia
> paper
>
>
> "Thomas R. Holtz, Jr." wrote:
>
> > Let's keep things in perspective: 5 m/s is still fast
for a big animal,
> and
> > that is BELOW the walk/run transition. Incidentally
(for thought
> > experiment's sake), if a _T. rex_ of MOR 555's size
could move at Fr = 3.8
> > (the dimensionless "speed" of Day et al.'s Middle
Jurassic tracksite),
> that
> > would be 9.1 m/s.
>
> So: Farlow, Robinson and Smith calculate that a safe speed
for a T.rex
> to avoid tripping would be around 35 KPH. These M.Jurassic
prints also
> seem to indicate a similar speed for a large theropod (9.1
m/s = 32.7
> KPH). Suggestive, non?
>
> > According to their model, _T. rex_ was not a fast
*runner*. This doesn't
> > mean it was slow! If MOR was doing 5 m/s, it could
still probably catch
> > most of the people on this list if it were chasing us!
>
> Indeed. Elephants don't "run", but they can get up one
hell of a speed.
> Plus they are also susceptible to fatal tripping, yet that
doesn't slow
> them down much.
>
> Lions and leopards are much slower than many of their
prey. In fact,
> ambush predators in general seem to be fairly robust
creatures - not
> unlike a certain large theropod? If you're not chasing
down gazelles for
> a living, why be an olympic sprinter?
>
> --
>
________________________________________________________________
>
> Dann Pigdon Australian Dinosaurs:
> GIS Archaeologist
http://www.geocities.com/dannsdinosaurs
> Melbourne, Australia
http://www.alphalink.com.au/~dannj/
>
________________________________________________________________
>
>
>
>
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