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Fish
Fossil Discovery Could Solve Evolution Mystery |
Posted:
04.10.06
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Scientists have discovered the fossils of a 375-million-year-old
fish that lived in water but moved on land that may be the "missing
link" between fish and walking land animals.
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The creature, a giant, scaly fish believed to be 4 feet to 9
feet long, lived in shallow water, scientists believe, but had
certain features of a mammal, including bones in its front fin
that look like a shoulder, an elbow, a forearm and a wrist.
 The
animal occasionally used its unique fins to move over land, says
Ted Daeschler, one of the paleontologists who made the discovery.
"And that's what is particularly important here. The animal
is developing features which will eventually allow animals to
exploit land," Daeschler told the NewsHour.
Scientists are whimsically calling it a "fishopod" --
part fish, part tetropod, or four-legged animal.
Scientists have believed for a long time that land animals --
first reptiles, then dinosaurs, and eventually even humans --
evolved from sea creatures, and the finding in the Canadian Arctic
could help prove it.
"It's an important new contribution to (understanding) a
very, very important transition in the history of life,"
Robert Carroll, a paleontology expert at McGill University in
Montreal, told the Associated Press.
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Tiktaalik |
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Scientists have named the fish Tiktaalik roseae, roughly meaning
large, freshwater fish found in the shallows, a name chosen from
the traditional language of the Nunavut Territory where it was
discovered.
Believed to be a meat eater, Tiktaalik had a flat, crocodile-like
head with eyes on top instead of on the side. It had a neck and
ribs and, like mammals, its head could move around on its shoulders.
It probably had lungs and gills allowing it to breath on land
and in water.
Researchers have not discovered the tail end of Tiktaalik's body
and so do not know what the tail or hind fins may have looked
like.
The animal would have spent most of its time in the water but
could move onto land for brief excursions.
"Tiktaalik was probably an unwieldy swimmer," John
Maisey, a paleontologist at the American Museum of Natural History
in New York, told Nature Online News.
"Tetrapods did not so much conquer the land, as escape from
the water," he added.
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From water
to land |
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The discovery is important for scientists.
 While
creatures known as transitional fish with features of both fish
and land dwellers have been found before, Tiktaalik is one of
the best examples.
"Tiktaalik fills that gap. It teaches us a lot about how
the features which the earliest tetropods would use to build a
limb and eventually come on land were first established in fish
living in shallow water," said Daeschler.
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Darwin's
theory |
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The scientists involved in the discovery have not directly entered
the creationist-evolution debate. But other scientists say the
finding bolsters Darwin's theory that life evolved from nature
and adapted over time.
Religious creationists, on the other hand, believe that humans
did not evolve from other animals, but were instead created by
God.
 Creationists
have claimed that the absence of transitional creatures weakens
Darwin's theory. Evolutionists say Tiktaalik is a key piece of
the evolution puzzle.
"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?" Michael Novacek, a paleontologist not
involved in the research, told the New York Times.
Some creationists remain unconvinced.
"This alleged transitional fish will have to be evaluated
carefully," Duane Gish, a retired official of the Institute
for Creation Research in San Diego, told the New York Times.
--
Compiled by Annie Schleicher for NewsHour Extra
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Joplin was able to rise from the ashes because of help from everyone. And I am eternally grateful to anyone who made that possible.
