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Re: leg injuries in large theropods, etc



On Sat, 9 Mar 1996, D. Tanke wrote:

>  I am curious to know whether those motorbike riders who related their
> accident experiences could enlighten us on any differing injuries between
> pavement wipe-outs versus those suffered by dirt-bike riders who are wiping
> out on softer and more yielding substrate (which would be more akin to the
> ground a tyrannosaur would land on in the event of a fall). I would expect a
> rider on smooth, regular pavement would be more likely to slide along,
> whereas softer irregular ground would invite more rolling, digging in and
> flipping over such as seen in racecars which get off the track and onto the
> grassed infield.

        When I was 18 I had a motorcycle accident which sent me skidding 
on my back  from the inside to the outside of a curve.  I managed to 
break a collar bone, but my leather jacket saved my back from getting too 
much gravel embedded in it.  This was "regular" pavement and it was my 
experience that so long as you can keep from rolling, you will simply 
slide until your momentum dissapates.
        More recently I attempted to drive a motorcycle through a 
mountain (I don't recommend this as a time saving strategy).  Striking 
the cliff face at an oblique angle sent me tumbling, flipping, and 
generally flopping along in a more haphazard fashion than my earlier 
accident.  Although my accident began on "regular" pavement, the damage 
to me and my poor bike were sustained on the "soft" shoulder of the road 
and the side of the mountain.  And although this accident was 
considerably worse, my injuries consisted of only a sprained ankle.  
However, I should qualify that by adding that I was wearing a helmet in 
this second accident.  The front and side of the helmet took a lot of 
punishment which my face would have otherwise.
        Maybe these stories aren't exactly appropriate for the dinosaur list, 
but the point is that, yes, high-speed tumbles on pavement tend to 
produce slides, and tumbles in more irregular areas tend to produce more 
irregular flipping.  I think the irregular flipping can cause much more 
damage, even if the surface is "softer" than pavement.
        However, I don't think race cars getting off pavement is a proper
analogy.  Race cars frequently have aerodynamic and ground effect devices
which are designed to keep the car glued to the track, and which only work
properly when the car is traveling forward and parallel to the road surface. 
When the attitude of the vehicle is changed relative to it's direction of
travel (even just from hitting a hard bump), these aerodynamic devices can
cause the car to fly up or tumble wildly.
        Tyrannosaurs and motorcyclists aren't usually encumbered with 
aerodynamic devices, so their "falling behavior" should be more analogous 
(allometry aside.)
        In any case, wiping out on pavement or dirt doesn't make much 
difference when you're traveling at 40 or 50 miles an hour.  Wiping out 
on water skiis can hurt at that speed.  And if you weigh 5 tons, wiping 
out at any speed is going to do some damage.
        I'd also like to point out that tyrannosaurs weren't the only
bipedal predators, and _T. rex_ especially is a size extreme.  Perhaps it 
would be better to look for falling injuries in smaller theropods first.  
I think that concentrating on the biggest beasts on the block will tend 
to give a skewed view of things.  Even professional basketball players 
have a much harder time falling down than a short guy like me.

-Mikiel