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Re: _T. rex_ strikes ( was Ceratopsian frills)

At 04:42 PM 12/21/96 -0500, Steve Throop wrote:

>Stan Friesen wrote:
>> An edmontosaur is a *huge* animal (it makes a moose look small).
>> It seems likely that T. rex could manage to move fast enough to
>> contact such an animal.  And I doubt that great precision was
>> necessary - repeated slashing bites would bring down the prey
>> just as thoroughly as a choking bite such as used by cats.
>I don't know that an edmontosaur weighed, but it looks significantly
>smaller than _T rex_. 

Well, my memory said different, so I looked it up in three different
references. I get various sizes for Edmontosaurus of 42, 43, and 46
feet. I get various sizes for T. rex of 39, 42, and 49 feet. If we dismiss
the high end as probably overenthusiastic estimates, we still get
Ed and Rex within a few percent of each other.
        A note to Steve: why stick your neck out like that, when it's so
easy to just do the barest minimum of research? It took me five minutes
to look those up...

> Perhaps _T rex_ could crush its neck in one quick bite.  It looks
>like it didn't have the mass or the bones to cause catastrophic
>dental failure.  (Losing one or two teeth at a time, like a child,
>would have been okay.)

I think the comparison to a child's losing teeth leads down a dangerously
wrong path. Tyrannosaurs had an ongoing resupply of growing teeth, unlike
humans, child or adult. "Catastrophic dental failure" in a T.rex would have
to involve breaking enough teeth that he would be unable to hunt or eat,
for long enough to starve. Seems unlikely -- and most T.rex specimens
I'm familiar with seem to have a well-equipped dentary. 

>Best of all, it looks innocuous!  I understand its tail had limited
>motion, and I don't think bipeds could use their tails as effectively as
>quadrupeds, anyway.  

What are you saying here? That T.rex (biped) couldn't "use its tail as
effectively" (for balance? combat? what?) as Ed (probably primarily a
quadruped, for walking)? 

>If I were a _T rex_, that's what I'd eat even if the others called me a
>wimp.  Did no species prey on the more dangerous game?

One zebra looks innocuous. Three hundred of them, stampeding toward you,
look VERY scary. When a predator preys on herd animals, it tries to
separate an individual, usually slower (old, injured, sick, or juvenile), from
the herd. The herd animal's defense is twofold: 1) By being one in a hundred,
the odds are about 100:1 that a given predator will bet somebody else (and
by staying toward the center, you improve those odds). 2) By not being
separated from the herd, you retain the strength of numbers -- a stampeding
herd of just about anything is pretty formidable.
        And finally, given that Ed WAS about the same size as Rex, let's not
underestimate the simple defense of swerving into the attacker, possibly
knocking him over. While I don't believe that falling Tyrannosaurs were as
liable to injury as some do, it would at least delay the pursuit, or possibly 
give an opportunity for trampling -- which WOULD probably be fatal.

>As for the latter... Five tons?  Very agile?  Built to turn and lunge? 
>Four-foot horns on an eight-foot skull?  Able to catch me in a sprint? 
>A beak that looks like it could bite off a utility pole?  
>Is that why _T rex_  skeletons never seem to be complete?  I'd have to
>have his written guarantee that he wouldn't get upset when I bit him. 
>If only I knew how to give him a bad knee before I introduced myself...

Seems to me that a Triceratops running AWAY from Rex presents a very
good target -- see G. Paul's drawings in PDW. As far as completeness of
skeletons goes, I hope that's a joke -- otherwise the taphonomy doesn't
make ANY sense.
        And I agree with Stan Friesen -- simple repeated bites on a given 
individual will weaken it enough that the attack need not be immediately
fatal. Suppose the tyrannosaur just hung around the periphery of the herd,
attacking as opportunity presents itself. Some failures. Some immediate
fatalaties. But probably a number of simple injuries -- survivable ones that
might slow the animal next time, make it easier to separate from the herd.
And a festering wound would be easy for Rex to track with its (we all agree?)
powerful olfactory system.

Wayne Anderson