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Re:big duckbills (was _T. rex_ strikes)



Wayne Anderson wrote:

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

> >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...

You caught me with my neck way out!  I envy you for having the facts at
hand.  Here's the kind of stuff that's in my books:

"_Tyrannosaurus Rex_, the fifty-foot-long Cretaceous killer with
seven-inch teeth, was really just a sophisticated variation on the basic
predator plan first evolved a hundred million years earlier in the Late
Triassic.  Bone by bone, _Tyrannosaurus Rex_ was fundamentally little
different from its ancient Triassic ancestor." (Robert Bakker)

Where are the facts?  Assuming the Late Triassic was 225 million years
ago, one might infer that _T rex_ lived 125 million years ago.  One
might infer that the unnamed Triassic ancestor was also a tyrannosaur.

This passage seemed significant, but it was hard to locate because it's
not indexed and not in a chapter where one might expect it.  I have
several books like that.  It's as if the authors tease rubes like me in
a game of keep-away.  When they let you grab a fact, they're likely to
declare it heresy in two years.  

Have others experienced such frustrations?  The more I read, the more
illiterate I become.  That's why I'm vague and confused about cladistics
and chronology.

I'd better add _size_ to the list.  I can trace my blooper to L. B.
Halstead, D. Sc., Departments of Geology and Zoology, University of
Reading, England.  "_Dinosaurs_  is intended to be the major reference
work on the different kinds of dinosaurs that are known."

His scale drawing of a tyrannosaur shows one 17 m (55 ft) long. 
According to these drawings, most duckbills were about the same length
as the 9 m ( 30 ft) _Edmontosaurus_.  His text implies that most
duckbills weighed about 3 tonnes.  

Halstead says, "_Shantungosaurus_ has the distinction fo being the
largest known hadrosaur.  [...] The striking feature of it is its
significantly greater size, being over 12 m (40 ft) in length."

Thanks for exposing this hoaxster.  He really had me going!  When you're
as gullible as I am, you can't afford to take yourself seriously.  I
wonder if there is even a University of Reading!

> 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.

Typically, a child loses one tooth at a time, and it's because a
replacement is growing in.  

Big gaps in fossil teeth would have implied that _T rex_ did not subdue
huge, powerful prey before clamping down on its bones.

> >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)?

I'm glad you brought that up.  A tractor with a light front end can
swing sideways with fatal results.  I keep hundreds of pounds of iron
bolted to mine, to make it a solid "quadruped."  A crocodile seems like
that, with plenty of weight to hold its front feet in place when it
swings its tail hard.  The apparent lack of weight on a duckbill's front
feet makes me think its tail couldn't have been swung as hard as a
crocodile's --- even if its tail had been flexible.

> One zebra looks innocuous. Three hundred of them, stampeding toward
> you, look VERY scary. [...] 2) By not being separated from the herd,
> you retain the strength of numbers -- a stampeding herd of just
> about anything is pretty formidable.

Could  _T rex_ induce prey to chase him?  What a scheme!  Like a quail,
he might pretend to be crippled so they would keep chasing him.  Then,
when they were too worn out to resist, he'd stop for lunch.  That crafty
devil!  No wonder he was always grinning! :)

> >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.

Couldn't the absence of a few bones be a valuable clue for a
taphonomist?

_Triceratops_ must have been very easy prey.  The same short legs and
eight-foot skull that would make it explosive in a fight would make it
fizzle in a chase.

Why would an animal equipped like _Triceratops_ turn tail?  Perhaps the
answer has appeared on the list.  If I've got it right, the frill and
the horns were decorations to look sexy.  This animal would run away to
avoid getting tyrannosaur blood all over its attractive horns and beak! 
:)

Happy New Year!

-Stephen Throop

"The problem with humor is that people take it so seriously." (Clyde and
Sadie)