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Newly found species fills evolutionary gap between fish and land animals
EurekAlert (AAAS) ^ | 05 April 2006 | Staff

Posted on 04/05/2006 10:32:31 AM PDT by PatrickHenry

Paleontologists have discovered fossils of a species that provides the missing evolutionary link between fish and the first animals that walked out of water onto land about 375 million years ago. The newly found species, Tiktaalik roseae, has a skull, a neck, ribs and parts of the limbs that are similar to four-legged animals known as tetrapods, as well as fish-like features such as a primitive jaw, fins and scales.

These fossils, found on Ellesmere Island in Arctic Canada, are the most compelling examples yet of an animal that was at the cusp of the fish-tetrapod transition. The new find is described in two related research articles highlighted on the cover of the April 6, 2006, issue of Nature.

"Tiktaalik blurs the boundary between fish and land-living animal both in terms of its anatomy and its way of life," said Neil Shubin, professor and chairman of organismal biology at the University of Chicago and co-leader of the project.

Tiktaalik was a predator with sharp teeth, a crocodile-like head and a flattened body. The well-preserved skeletal material from several specimens, ranging from 4 to 9 feet long, enabled the researchers to study the mosaic pattern of evolutionary change in different parts of the skeleton as fish evolved into land animals.

The high quality of the fossils also allowed the team to examine the joint surfaces on many of the fin bones, concluding that the shoulder, elbow and wrist joints were capable of supporting the body-like limbed animals.

"Human comprehension of the history of life on Earth is taking a major leap forward," said H. Richard Lane, director of sedimentary geology and paleobiology at the National Science Foundation. "These exciting discoveries are providing fossil 'Rosetta Stones' for a deeper understanding of this evolutionary milestone--fish to land-roaming tetrapods."

One of the most important aspects of this discovery is the illumination of the fin-to-limb transition. In a second paper in the journal, the scientists describe in depth how the pectoral fin of the fish serves as the origin of the tetrapod limb.

Embedded in the fin of Tiktaalik are bones that compare to the upper arm, forearm and primitive parts of the hand of land-living animals.

"Most of the major joints of the fin are functional in this fish," Shubin said. "The shoulder, elbow and even parts of the wrist are already there and working in ways similar to the earliest land-living animals."

At the time that Tiktaalik lived, what is now the Canadian Arctic region was part of a landmass that straddled the equator. It had a subtropical climate, much like the Amazon basin today. The species lived in the small streams of this delta system. According to Shubin, the ecological setting in which these animals evolved provided an environment conducive to the transition to life on land.

"We knew that the rocks on Ellesmere Island offered a glimpse into the right time period and the right ancient environments to provide the potential for finding fossils documenting this important evolutionary transition," said Ted Daeschler of the Academy of Natural Sciences in Philadelphia, a co-leader of the project. "Finding the fossils within this remote, rugged terrain, however, required a lot of time and effort."

The nature of the deposits where the fossils were found and the skeletal structure of Tiktaalik suggests the animal lived in shallow water and perhaps even out of the water for short periods.

"The skeleton of Tiktaalik indicates that it could support its body under the force of gravity whether in very shallow water or on land," said Farish Jenkins, professor of organismic and evolutionary biology at Harvard University and co-author of the papers. "This represents a critical early phase in the evolution of all limbed animals, including humans--albeit a very ancient step."

The new fossils were collected during four summers of exploration in Canada's Nunavut Territory, 600 miles from the North Pole, by paleontologists from the Academy of Natural Sciences in Philadelphia, the University of Chicago and Harvard University. Although the team has amassed a diverse assemblage of fossil fish, Shubin said, the discovery of these transitional fossils in 2004 was a vindication of their persistence.

The scientists asked the Nunavut people to propose a formal scientific name for the new species. The Elders Council of Nunavut, the Inuit Qaujimajatuqangit, suggested "Tiktaalik" (tic-TAH-lick)--the word in the Inuktikuk language for "a large, shallow water fish."

The scientists worked through the Department of Culture, Language, Elders and Youth in Nunavut to collaborate with the local Inuit communities. All fossils are the property of the people of Nunavut and will be returned to Canada after they are studied.

###

The team depended on the maps of the Geological Survey of Canada. The researchers received permits from the Department of Culture, Language, Elders and Youth of the Government of Nunavut, and logistical support in the form of helicopters and bush planes from Polar Continental Shelf Project of Natural Resources Canada. The National Science Foundation and the National Geographic Society, along with an anonymous donor, also helped fund the project.


TOPICS: Heated Discussion
KEYWORDS: 375millionyears; coelacanth; crevolist; lungfish; tiktaalik; transitional
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To: ahayes
Ping to self

That'll make you go blind and grow hair on your palms, or so they say.

341 posted on 04/05/2006 2:50:42 PM PDT by Ichneumon
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To: AmericaUnited
Supposedly learned individuals put out this drivel and then other supposedly learned individuals soak it up like sponges...

Amen!

If it is not some evolution nonsense, it is nonsense like the De Vinci Code.

Anything but the truth. (Rom.1:22)

I find it interesting that the natives gave the name of the fossil the name of a fish.

342 posted on 04/05/2006 2:51:22 PM PDT by fortheDeclaration (Gal. 4:16)
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To: VadeRetro

When there's no debate it's hard to lose. I guess I'm just one big loser.


343 posted on 04/05/2006 2:51:45 PM PDT by furball4paws (Awful Offal)
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To: PatrickHenry
Tiktaalik was a predator with sharp teeth, a crocodile-like head and a flattened body.

So it had crocodillian carachteristics but not human? All we need now is a crocodile that walked upright and/or had opposable thumbs. The tiktaalik is hardly a missing link. There are lots of amphibious animals that may have evolved from aquatic animals as a result of drought. I saw a documentary not long ago about some modern-day aquatic animal in Africa that either evolves into an aquatic animal or amphibious animal based soley on how rainy the breeding season is. Sorry, don't remember what channel, the name of the animal or have a link. But I did see it so it must be true! :-)

344 posted on 04/05/2006 2:56:44 PM PDT by PistolPaknMama (Al-Queda can recruit on college campuses but the US military can't! --FReeper airborne)
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To: grapevine
I was gonna' say "monkies the world over just heaved a huge sigh of relief."

HA Ha best joke of the day.

345 posted on 04/05/2006 2:59:06 PM PDT by jec41 (Screaming Eagle)
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To: PistolPaknMama

The tiger salamander is one such critter:

http://www.npwrc.usgs.gov/narcam/idguide/atigrin.htm

Can be a nasty predator and cannibal or a docile aquatic thingy, depending on the environment. Probably not what you were referring to, but similar, no doubt.


346 posted on 04/05/2006 3:01:41 PM PDT by furball4paws (Awful Offal)
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To: onedoug

Yeah. I posted it because it was funny


347 posted on 04/05/2006 3:02:36 PM PDT by dennisw (If you know the enemy and know yourself you need not fear the results of a hundred battles-Sun Tzu)
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Comment #348 Removed by Moderator

To: yellowdoghunter

I read on some of these threads that some consider philosophy to be a waste of time because they don't understand it.

It surprises me because science began as a philosophy. The way that science gathers information seems to be derived from Epistemology.


349 posted on 04/05/2006 3:04:34 PM PDT by Conservative Texan Mom (Some people say I'm stubborn, when it's usually that I'm right!)
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To: All
We're in the smokey backroom. I therefore abandon thread!
350 posted on 04/05/2006 3:13:46 PM PDT by PatrickHenry (Yo momma's so fat she's got a Schwarzschild radius.)
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To: Conservative Texan Mom
Just wondering, what is the simplest life form that is able to be linked to the chain of evolution thus far?

The prokaryotes (single-celled organisms without membrane-bound organelles), kingdoms Eubacteria and Archaea. These at one point had a common ancestor but it is lost. Eukaryotes (organisms with membrane-bound organelles) are thought to have evolved through some type of symbiotic arrangement between bacteria and archaebacteria. The simplest version involves an archaebacterium engulfing an bacterium, the bacterium lives inside the host and provides oxygen scavenging, hydrogen, or some other benefit. Over time many genes on the engulfed bacterium's genome become transferred to the nucleus (there are varying theories about how that arose too), new genes arise, and eventually we get the modern eukaryotes with mitochondria.

Support for this idea includes the fact that eukaryotes like us share many metabolic enzymes with bacteria, but our mechanisms for gene transcription and translation are more like the archaebacteria's.

351 posted on 04/05/2006 3:16:50 PM PDT by ahayes
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To: PatrickHenry

Aw c'mon, the smokey backroom is where all the Earth moving deals are made.


352 posted on 04/05/2006 3:17:24 PM PDT by furball4paws (Awful Offal)
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To: tallhappy
Where did I say or indicate anything was incorrect (or correct for that matter)?

That's right. You said nothing of substance at all.

353 posted on 04/05/2006 3:18:42 PM PDT by Right Wing Professor
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To: tallhappy
Where did I say or indicate anything was incorrect (or correct for that matter)?

That's right. You said nothing of substance at all.

354 posted on 04/05/2006 3:18:44 PM PDT by Right Wing Professor
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To: Conservative Texan Mom; PatrickHenry

Science does have an epistemology - it's called the Scientific Method. The Scientific Method is often an object of derision from the Creo crowd who have no useful alternative, but it is sound and well tested over hundreds of years.

Dare I say it - OK, Descartes.

OK PH you can abandon the thread now.


355 posted on 04/05/2006 3:20:51 PM PDT by furball4paws (Awful Offal)
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To: yellowdoghunter
And since this is America, we are all free to believe as we see fit.

Yes there are a lot that feel that way. Some criminals believe its OK to kill others. Some who's dog was killed 10 years ago still believe he is playing out side. However science is not based on your beliefs. That is philosophy. Science was designed as a method to observe material facts and give evidence and explanation of the fact. It does not care what is faith and belief. It would seem that after all that collage one should know the difference between the methods of philosophy, science, and mathematics. It should have been learned in High School.

356 posted on 04/05/2006 3:21:32 PM PDT by jec41 (Screaming Eagle)
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To: ahayes

Also the similarity of of some of our mitochondrial genes with those of procaryotes.


357 posted on 04/05/2006 3:22:59 PM PDT by furball4paws (Awful Offal)
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To: King Prout

Unfortunately I think that entertainment masquerading as science has been a catalyst for much of this misunderstanding regarding evolution. I am a Christian, and I believe evolution occurs. The evidence is undeniable. I do not know to what degree.


(11 Then God said, "Let the land produce vegetation: seed-bearing plants and trees on the land that bear fruit with seed in it, according to their various kinds." And it was so.)

Let the land produce? Something to think about.

and again,

(And God said, "Let the land produce living creatures according to their kinds: livestock, creatures that move along the ground, and wild animals, each according to its kind." And it was so.)

Interestingly enough, it does not word it this way for life in the oceans. Here, it suggest direct creation. Which is in line with the Theory of Evolution.

I do part with ToE on the evolution of man. But, I have no scientific evidence to back it up, so I won't argue it on this forum.


358 posted on 04/05/2006 3:24:02 PM PDT by Conservative Texan Mom (Some people say I'm stubborn, when it's usually that I'm right!)
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To: Dimensio
Do you have actual statements of substance that you have not yet provided

My first WAS as much a statement of substance as this nonsense:

Huge predators would have lurked in Tiktaalik's rivers and lakes, study co-leader Shubin says—perhaps one reason why Tiktaalik appears to have been headed for land.

Yea! I'm sure this creature was thinking "Gee, it's very vicious out here in the deep. I think I'll learn to grow mini-legs over the next several million years so I can take a look-see on land and see if it's safe. If so, I'll then spend another several million years morphing myself into a 'land critter'"

And you call that substative?

359 posted on 04/05/2006 3:26:35 PM PDT by AmericaUnited
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To: AmericaUnited
Today's world is full of your type of 'learned' individual, ones with lots of facts and figures crammed into their heads by professors ( of which 99% of them could never make it in the real world).

No, it's not. It's full of loud-mouth idiots whose ignorance is inversely proportional to the amount they know. There are way too few people who know anything much about science.

360 posted on 04/05/2006 3:27:51 PM PDT by Right Wing Professor
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