RE: Muscles : Most annyoing question in DML history!

["Tracy L. Ford" <dino.hunter@cox.net>]

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
dexter dexter
Sent: Wednesday, April 03, 2002 7:45 PM
To: dinosaur@usc.edu
Subject: Muscles : Most annyoing question in DML history!

http://hometown.aol.com/lestatk/

Okay, this has been bothering me for a while. For the last
two years or so, I keep hearing t-rex biased fans claiming
that the big guy was "more powerful, faster, more advanced,
more gracile[etc.]" than G. carolinii, you get the picture ?
Now, while I agree it certainly had more gracile limb
proportions and was most likely faster, where comes the
belief that it was more powerful ? Let alone
>proportionally< more (in relative - body weight)? While I
am aware that some of them don't know much about
paleontology, and my strong suspicion is that they base this
only on bite force (G. Erickson's study, I beleive ... So
they took for fact that _G. carolinii_ had the same bite
force as weaker _A. fragilis_), where comes this belief ? Is
this something I completely haven't heard about ? Some sort
of study compairing both animals in "power-to-weight" ratio.

(Now, I am aware the Gig/Rex questions are a real pain for
everyone on the DML, it's something I've been curious about
for awhile...)

Thanks,
Thomas Miller<<

One of the things is jaw muscle mass and T. rex has/had a much large muscle
attachment area for the lower jaw than does Giganotosaurus. Looking at the
skull ventrally, or even from the posterior the skull of T. rex is like a
trapezoid, while Giganotosaurus is more square (which is typical for
theropods or dinosaurs in general). The lower jaw muscles expanded the lower
part of the skull in T. rex. IMHO as the lower jaw expanded without
expanding the upper portion of the skull (I've scaled up an Allosaurus skull
to match the length and width (dorsally) of T. rex) the upper portion
remained the same, but pinched the area in front of the orbits giving them
the 'stereo' vision (so secondarily obtained and not do to hunting). Any
allosaurid or 'lower' or 'primitive' theropod that has stereovision is
wrong. You don't need stereovision to hunt.

Anyway back to your question. T. rex also as we all know, had larger
'thicker' teeth, larger thicker jaw muscles (several bones that have
punchers from T. rex teeth) so it can be concluded that it had a more
'powerful' bite. The tests done with T. rex teeth to show the bite force IB
(I believe) should be expanded to show the bite force of the 'whole' jaw and
not just the single tooth. Like crocodiles, theropods had extremely downward
force in the jaws, but I wouldn't doubt that someone could hold the jaw
closed because they had less muscle mass to open the jaw. Just imagine a JP
movie with someone who has there arms wrapped around the jaws of T.rex and
it can't open its jaws.

Now onto Giganotosaurus. I've been thinking about how the lower back end of
the skull which has expanded. Which is unusual. Would the expanding of the
skull backward allow for more muscle mass without increasing the height of
the skull? The teeth are more feeble than T. rex but could have had a strong
(not stronger) bite.

Also, IMHO next muscles come into the fray. T. rex had larger neck muscles
also.

Tracy L. Ford
P. O. Box 1171
Poway Ca  92074