Re: OT - Gap closed

Sorry for the top post, but, I thought this was going to be a post about
Condi and her dentist.



Dewey wrote:
One of the main arguments proponents of intelligent design and
creationism make is that there are "gaps" in the fossil records.
Their # 1 example is that there has never been a fossil found that
demonstrates sea creatures changing into land creatures. Well, file
that argument in the trash bin of ignorance.

http://www.nytimes.com/2006/04/05/science/05cnd-fossil.html

April 5, 2006
Scientists Call Fish Fossil, 375 Million Years Old, 'Missing Link'
By JOHN NOBLE WILFORD
Scientists have discovered fossils of a 375 million-year-old fish, a
large scaly creature not seen before, that they say is a long-sought
"missing link" in the evolution of some fishes from water to a life
walking on four limbs on land.

In addition to confirming elements of a major transition in evolution,
the fossils are widely seen by scientists as a powerful rebuttal to
religious creationists, who hold a literal biblical view on the
origins and development of life.

Several well-preserved skeletons of the fossil fish were uncovered in
sediments of former stream beds in the Canadian Arctic, 600 miles from
the North Pole, it is being reported on Thursday in the journal
Nature. The skeletons have the fins and scales and other attributes
of a giant fish, four to nine feet long.

But on closer examination, scientists found telling anatomical traits
of a transitional creature, a fish that is still a fish but exhibiting
changes that anticipate the emergence of land animals - a predecessor
thus of amphibians, reptiles and dinosaurs, mammals and eventually
humans.

The scientists described evidence in the forward fins of limbs in the
making. There are the beginnings of digits, proto-wrists, elbows and
shoulders. The fish also had a flat skull resembling a crocodile's, a
neck, ribs and other parts that were similar to four-legged land
animals known as tetrapods.

The discovering scientists called the fossils the most compelling
examples yet of an animal that was at the cusp of the fish-tetrapod
transition. The fish has been named Tiktaalik roseae, at the
suggestion of elders of Canada's Nunavut Territory. Tiktaalik
(pronounced tic-TAH- lick) means "large shallow water fish."

In two reports in Thursday's issue of the journal Nature, the science
team led by Neil H. Shubin of the University of Chicago wrote, "The
origin of limbs probably involved the elaboration and proliferation of
features already present in the fins of fish such as Tiktaalik."

Dr. Shubin, an evolutionary biologist, let himself go in an interview.
"It's a really amazing remarkable intermediate fossil - it's like,
holy cow," he enthused.

Two other paleontologists, commenting on the find in a separate
article in the journal, said that a few other transitional fish had
been previously discovered from approximately the same Late Devonian
time period, 385 million to 359 million years ago. But Tiktaalik is so
clearly an intermediate "link between fishes and land vertebrates,"
they said, that it "might in time become as much an evolutionary icon
as the proto-bird Archaeopteryx," which bridged the gap between
reptiles, probably dinosaurs, and today's birds.

The writers, Erik Ahlberg of Uppsala University in Sweden and Jennifer
A. Clack of the University of Cambridge in England, are often viewed
as rivals to Dr. Shubin's team in the search for intermediate species
in the evolution from fish to the first animals to colonize land.

In a statement by the Science Museum of London, where casts of the
fossils will be on view, Dr. Clack said the fish "confirms everything
we thought and also tells us about the order in which certain changes
were made."

H. Richard Lane, director of paleobiology at the National Science
Foundation, said in a statement, "These exciting discoveries are
providing fossil 'Rosetta Stones' for a deeper understanding of this
evolutionary milestone - fish to land-roaming tetrapods."

The science foundation and the National Geographic Society were among
the financial supporters of the research. Besides Dr. Shubin, the
principal discoverers were Edward B. Daeschler of the Academy of
Natural Sciences in Philadelphia and Farish A. Jenkins Jr., a Harvard
evolutionary biologist.

Michael J. Novacek, a paleontologist at the American Museum of Natural
History in Manhattan, who was not involved in the research, said:
"Based on what we already know, we have a very strong reason to think
tetrapods evolved from lineages of fishes. This may be a critical
phase in that transition that we haven't had before. A good fossil
cuts through a lot of scientific argument."

While Dr. Shubin's team played down the fossil's significance in the
raging debate over Darwinian theory, which is opposed mainly by some
conservative Christians in the United States, other scientists were
not so reticent. They said this should undercut the creationists'
argument that there is no evidence in the fossil record of one kind
of creature becoming another kind.

One creationist Web site (emporium.turnpike.net/C/cs/evid1.htm)
declares that "there are no transitional forms," adding: "For
example, not a single fossil with part fins part feet has been found.
And this is true between every major plant and animal kind."

Dr. Novacek responded in an interview: "We've got Archaeopteryx, an
early whale that lived on land and now this animal showing the
transition from fish to tetrapod. What more do we need from the fossil
record to show that the creationists are flatly wrong?"

Dr. Shubin and Dr. Daeschler began their search on Ellsmere Island in
1999. They were attracted by a map in a geology textbook showing the
region had an abundance of Devonian rocks exposed and relatively easy
to explore. At that time, the land was part of a supercontinent
straddling the equator and had a warm climate.

It was not until July 2004, Dr. Shubin said, that "we hit the
jackpot." They found several of the fishes in a quarry, their
skeletons largely intact and in three dimensions. The large skull had
the sharp teeth of a predator. It was attached to a neck, which
allowed the fish the unfishlike ability to swivel its head.

"Fish feeding in water readily orient the mouth toward food by
maneuvering the entire body," said Dr. Jenkins, who assisted in the
interpretation of the fossils. "The head is rigidly attacked to the
trunk by bones linking the skull and shoulder girdle, and thus fish
have no neck."

If the animal spent any time out of water, he said, it needed a true
neck that allowed the head to move independently on the body.

Embedded in the pectoral fins were bones that compare to the upper
arm, forearm and primitive parts of the hand of land-living animals.
The scientists said the joints of the fins appeared to be capable of
functioning for movement on land, a case of a fish improvising with
its evolved anatomy. In all likelihood, they said, Tiktaalik flexed
its proto-limbs primarily on the floor of streams and may have pulled
itself up on the shore for brief stretches.

In their journal report, the scientists concluded that Tiktaalik is an
intermediate between the fish Panderichthys, which lived 385 million
years ago, and early tetrapods. The known early tetrapods are
Acanthostega and Ichthyostega, about 365 million years ago.

Tiktaalik, Dr. Shubin said, is "both fish and tetrapod, which we
sometimes call a fishapod."


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