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Re: A whole lot of trouble....



[This message makes me uneasy because it looks like there are some
 half-truths in it -- half-truths that point towards a Ted Holden-ish
 fantasy.  (Those of you who don't know who Ted Holden is, please
 thank your lucky stars!)  If this thread starts drifting further
 towards any silly catastrophist scenarios, I'll start rejecting
 messages right and left.  Let that be a warning (or reassurance) to
 anyone out there who thinks (or fears) that this list will follow the
 path that sci.bio.paleontology followed... -- MR ]

On October 28, Peter Buchholz said a person could get into a lot of
trouble for proposing a theory that annoyed scientists.  What fun!

He suggested that dinosaurs first had feathers.  They would flail their
limbs for balance when they jumped from limb to limb.  That's how they
learned by accident to glide.  Then the gliders evolved the structures
necessary for powered flight.

That explanation seems way out on a limb.  It's like expecting flying
squirrels to evolve into bats.  As the farmer replied when asked
directions, "You can't get there from here."  

The requirements for flight are so different from those for gliding that
before gliders ever learned to fly, countless of generations would have
had to evolve senseless changes.

The same consideration argues against the theory that flight evolved
from fleeing (i.e. flight).  Until a species could fly, the evolving
changes would have made it a slower runner.  Flying dinosaurs would have
lost their ancestors before the ancestors had any offspring.

The big picture is a bigger puzzle.  Look at scale.  For animals of the
same proportions, mass varies as the cube of linear size.  Surface area
varies as the square of size.  That means wing loading varies in
proportion to size.  Meanwhile, the force to vibrate a wing at a certain
frequency varies as the fourth power of size.  

This means a wing on a larger animal must maintain more pressure but
can't be flapped as fast.  That's why it would take a miracle for a big
bug to fly in the manner of a housefly.  It's also why the bumblebee is
thought to be as large as possible for a flying animal of that design.  

Still, in the dinosaur days, there were flying bugs that were built like
modern species except that they were much bigger, perhaps ten times. 
How could they possibly have flown?

In scale, flying dinosaurs present bigger problems.  One had a wingspan
of 51 feet!  In World War Two, an airplane that big would have needed
two engines, 3,000 horsepower, and thousands of feet of runway.  How
could an animal that big have produced enough power to fly?  Where could
it have attained the necessary speed?  How could its wings have been
strong enough even to glide?

By contrast, a model airplane the size of  a typical hawk can take off
in two feet with only the power of a twisted rubber-band.  That's the
effect of scale.  

A bird with a five-foot span has a hard time taking off because its mass
is so great and its wings are so slow.  How could a dinosaur with 1,000
times as much mass and much slower wings ever have flown?

Here's another puzzle.  It seems that all flying dinosaurs had long,
heavy tails.  Modern land animals carry only little tails, and birds use
feathers for tails.  How could a dinosaur have flown with all that
weight?  It's even harder to understand why something as unsuited to
flight as a big tail didn't soon evolve to a little tail.  Instead, it
seems that flying dinosaurs kept their big tails for millions of years,
until they became extinct.

The origins of flight present us with several impossibilities.  Flight
is only one area where the evidence of dinosaurs is impossible.  If the
evidence is correct, then it seems that there must be a big mistake in
our fundamental assumptions about the environment of the dinosaurs.

Here's how Rob Meyerson, the distinguished orphan vertebrate, quoted
Sherlock Holmes the other day: "It is fatal for a researcher to develop
a theory before all the facts are in, because one ultimately tries to
twist facts to fit theories, rather than develop theories to fit the
facts."  

Don't worry.  I won't propose a theory.  As you no doubt see, I'm a
timid fellow who would *hate* to annoy anyone.

- Stephen Throop

"Just remember, America reaches from the tip of South America to the tip
of North America with Central America in between, but as long as we
remember we are citizens of the United States, there is no country in
the world that can top that image." :)