T-rex. shoulder rolls

[rstephen@cswnet.com (Roger A. Stephenson)]

Hello all,

 Jeffrey Martz asked
>Exactly how does a tyrannosaur "turn on a shoulder"?<

In my origional posting I suggested there were built-in self preservation
techniques concerning falls to T-rex. in reference to the crash and burn
article appearing in the April issue of Discover magazine.

If a T-rex. were to sense a loss of balance, while running, I submit that
if it had time to change its attitude it would. How? Well, if there was
time to allow it the T-rex. might try to orient its body to spread the
brunt of the force across the side of its body and not plow a ditch with
its face. I do know T-rex had no "shoulders" as we understand them, and was
only using that term to simplify the idea. The force of impact would be the
same, however the concentration of this force would be spread over a wider
area and therefore decreasing the likelyhood of serious injury. If this set
up a rolling motion the T-rex. might be able to use his feet to arrest the
roll rather quickly.

Being an ex-biker (motorcyclist) and having crashed at speeds in excess of
70 MPH, I can attest to impact from personal experience. Even with
protective headgear and clothing the risk of life threatening injury was
very real. Without thinking the problem through I tried to keep my head
away from impacting the pavement, instinctively. In T-rex. I envision
similar efforts in self preservation. Yes T-rex outwieghed me by several
orders of magnitude, but his bones were also stronger. Forward momentum can
actually be a plus in falling at high speed, to some extent. Instead of
slamming into the ground one tends to skip like a stone across water, and
this further distributes the impact over time and distance. I broke three
ribs and dislocated a shoulder in a 10 MPH fall, while coming through a 70
MPH fall with only pavement rash.

In private communication with Dr. Farlow I am gaining access to his work,
and after examination I MAY change my thinking.

Roger A. Stephenson
rstephen@cswnet.com