Newly found species fills evolutionary gap between fish and land animals

EurekAlert (AAAS) ^ | 05 April 2006 | Staff

[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.

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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.

[From many - one.]

Browsing a magazine at the airport and saw an article about a very unusual large virus that shares some markers. They called my flight, but more info should be out there somewhere. I'm off again so can't follow up.

[muawiyah]

Dimensio ~ there you go again pointing to "reality". Which "reality" would that be? Is that the one where the Universe is made up of stuff we can measure, examine, touch, feel, see and sense?

Or, is it the one where (let me correct the number here) about 5% is made up of such examinable stuff, and the other 95% is composed of invisible, untouchable, unmeasurable dark energy and dark matter?

Does your "reality" have 3 or 4 dimensions, or 11 dimensions?

Please don't bring "reality" into these threads ~ it just raises more questions that can't be answered.

[muawiyah]

After 500+ posts, don't think of my last post as a hijacking.

[muawiyah]

There's also this problem with living in lateritic soil. Much of Africa, as well as the American South, have such soils.

[muawiyah]

Only when you redefine evolution as a change in a single code unit in a single gene ~ otherwise, using Darwin's title for it "the origin of species", no one has seen it.

[muawiyah]

You simply cannot substitute the word "evolution" with the word "change" without distorting the argument.

It's like trying to have your cake and eat it too.

Does not compute. Does not compute.

[CarolinaGuitarman]

"Only when you redefine evolution as a change in a single code unit in a single gene ~ otherwise, using Darwin's title for it "the origin of species", no one has seen it."

Darwin called it the transmutation of species, or descent with modification. Evolution was not his term.

That being said, new species have been observed.

[dmz]

I was beautifully and wonderfully made in God's image.
____________

But where's your proof? That's only a theory.

[Fester Chugabrew]

. . . as science is limited to observations of the inside from the inside.

If there is any sidestepping here it is on the part of those who fail to acknowlege to subjective nature of the observer, and the emotional attachment one may have to his perceptions. Evolutionists are champions at hiding their biases while pounding their chests as if they alone hold the key to objective interpretation of the evidence. At least creationists honestly admit they subject themselves to a text they themselves did not spin out of whole cloth. Evolutionists have no guide other than their own opinions and what appears to be consensus among like-minded ideologues. In short, a science that depends upon human observers is no more sound than a science that proceeds on the basis of outside revelation.

[muawiyah]

Let's turn this on it's head. If "Occam's razor demands that ID be discarded until such time it makes a testable claim", then, given the existence of ADM and its extensive use of recombinant DNA technology to create new/modified lifeforms (Frankenfood to Europeans), then, ID must be correct (pointing to ADM as the "intelligent designer").

That's why you don't want to use that particular argument ~ it's of value if and only if we have a static Universe. Since we have a constantly changing Universe, which may even have variations in the speed of light over time (and all the other kinds of changes you might have with that sort of thing depending on when you live in the Universe), we really do need to stick with arguments that accommodate change.

This suggests, BTW, that Occam's razor is a fundamentally flawed doctrine and should, itself, be discarded.

[Sola Veritas]

"Humor has to have some basis in reality. The post in question didn't."

Of course, that is your opinion, not necessarily fact - I don't say that to stir the pot but respectfully. However, in that I try to avoid intentionally irritating someone, I probably shouldn't have posted my affirmation on that post. I have my weak moments.

I think all sides here need to chill a little. We argue with each other, and it never gets anything accomplished. We are all pretty entrenched in our relative positions. I sometimes marvel at the amount of time I waste posting here on FR on this topic.

[CarolinaGuitarman]

"If there is any sidestepping here it is on the part of those who fail to acknowlege to subjective nature of the observer, and the emotional attachment one may have to his perceptions."

That's why science relies on the independent verification of many observers, not just one.

"Evolutionists are champions at hiding their biases while pounding their chests as if they alone hold the key to objective interpretation of the evidence."

So you claim.

"At least creationists honestly admit they subject themselves to a text they themselves did not spin out of whole cloth."

So you claim.

"Evolutionists have no guide other than their own opinions and what appears to be consensus among like-minded ideologues."

No, there's objective reality. There's evidence crosschecked by many individuals, some who are deeply opposed to each other's theories.

"In short, a science that depends upon human observers is no more sound than a science that proceeds on the basis of outside revelation."

You are arguing for a purely postmodernist, completely relativistic model for the acquisition of knowledge. According to what you just said, all knowledge claims have equal truth values. This is obviously false.

[Elsie]

"A" link, but not "the" link -- a chain has many links, and so does an evolutionary sequence. I>

And, as always, all chains has a weak one.

[ventana]

" "A" link, but not "the" link -- a chain has many links, and so does an evolutionary sequence."

Does raise a question though.

If the tree of life takes two forks, and one fork develops a lung but no articulated fin structures, while a seperate fork develops a shoulder-elbow-wrist mechanism but no lung, how do those two seperated developments get back together?

Not to annoy, but someone could make a case for evidence of design right there. Is a lungfish's lung just like ours? Could seperate branches be reasonably assumed to develop identical complex mechanisms?

[CarolinaGuitarman]

"Let's turn this on it's head. If "Occam's razor demands that ID be discarded until such time it makes a testable claim", then, given the existence of ADM and its extensive use of recombinant DNA technology to create new/modified lifeforms (Frankenfood to Europeans), then, ID must be correct (pointing to ADM as the "intelligent designer")."

Um, no. How many times does it have to be said that the existence of ID among humans is in no way evidence for a designer that created the universe and guided the formation and then evolution of life? Apparently, not enough.

"That's why you don't want to use that particular argument ~ it's of value if and only if we have a static Universe."

It's of no value because it is logically fallacious.

"Since we have a constantly changing Universe, which may even have variations in the speed of light over time (and all the other kinds of changes you might have with that sort of thing depending on when you live in the Universe), we really do need to stick with arguments that accommodate change."

In other words, we can't know anything and any truth claim has equal validity? Sorry, post-modernism is not for me.
Your example also has nothing to do with whether there was a designer who created the universe and life.

"This suggests, BTW, that Occam's razor is a fundamentally flawed doctrine and should, itself, be discarded."

Or, it suggests you have made a logically fallacious argument.

[muawiyah]

Evolution theory no longer depends on "gradualism". In Darwin's time no one had the slightest clue about DNA. Now we do.

Still, we do have folks on the Evo side who keep arguing "gradualism" ~ just as we have folks on the Creo side who keep arguing that "gradualism" is wrong.

[muawiyah]

ADM creates new lifeforms all the time.

[Dawsonville_Doc]

RE: Backhistory and all that- we have a saying at my house, when watching television especially-

"Don't sweat the talking bears."
Sounds sort of like what you just explained.

Doc

[Elsie]

 

Links 'R' Us

 

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Mammal-Like Reptiles

As previously stated, a succession of transitional fossils exists that link reptiles (Class Reptilia) and mammals (Class Mammalia). These particular reptiles are classifie as Subclass Synapsida. Presently, this is the best example of th e transformation of one major higher taxon into another. The morphologic changes that took place are well documented by fossils, beginning with animals essentially 100% reptilian and resulting in animals essentially 100% mammalian. Therefore, I have chosen this as the example to summarize in more detail (Table 1, Fig. 1).  

M. Eyes =           ?           Nose =           ?        Teeth incisors = ?       K. Eyes =           ?           Nose =           pointy    Teeth incisors = small       J. Eyes =           Medium    Nose =           stubby        Teeth incisors = BIG       I. Eyes =           Medium    Nose =           less stubby    Teeth incisors = big       H. Eyes =           smaller    Nose =           more blunt    Teeth incisors = smaller         G. Eyes =           SMALL    Nose =           Pointer    Teeth incisors = Skinny           F. Eyes =           BIG    Nose =           Blunt    Teeth incisors = Thin         E. Eyes =           HUGE!    Nose =           pointy, again    Teeth incisors = Bigger         D. Eyes =           Smaller    Nose =           Getting wider    Teeth incisors = Bigger: two!         C. Eyes =           Huge, again!    Nose =           broader    Teeth incisors = very small         B. Eyes =           less huge    Nose =           less broad    Teeth incisors = ??         A. Eyes =           bigger again    Nose =           rounded    Teeth incisors = small

Skulls and jaws of synapsid reptiles and mammals; left column side view of skull; center column top view of skull; right column side view of lower jaw. Hylonomus modified from Carroll (1964, Figs. 2,6; 1968, Figs. 10-2, 10-5; note that Hylonomus is a protorothyrod, not a synapsid). Archaeothyris modified from Reisz (1972, Fig. 2). Haptodus modified from Currie (1977, Figs, 1a, 1b; 1979, Figs. 5a, 5b). Sphenacodo n modified from Romer & Price (1940, Fig. 4f), Allin (1975, p. 3, Fig. 16);note: Dimetrodon substituted for top view; modified from Romer & Price, 1940, pl. 10. Biarmosuchus modified from Ivakhnenko et al. (1997, pl. 65, Figs. 1a, 1B, 2); Alin & Hopson (1992; Fig. 28.4c); Sigogneau & Tchudinov (1972, Figs. 1, 15). Eoarctops modified from Broom (1932, Fig. 35a); Boonstra (1969, Fig. 18). Pristerognathus modified from Broom (1932, Figs 17a, b,c); Boonstra (1963, Fig. 5d). Procynosuchus modified from Allin & Hopson (1992, Fig. 28.4e); Hopson (1987, Fig. 5c); Brink (1963, Fig. 10a); Kemp (1979, Fig. 1); Allin (1975, p. 3, Fig. 14). Thrinaxodon modified from Allin & Hopson (1992, Fig. 28.4f);Parrington (1946, Fig. 1); Allin (1975, p. 3, Fig. 13). Probainognathus modified from Allin & Hopson (1992, Fig. 28.4g); Romer (1970, Fig. 1); Allin (1975, p. 3, Fig. 12). Morga nucodon modified from Kermack, Mussett, & Rigney (1981, Figs. 95, 99a; 1973, Fig. 7a); Allin (1975, p. 3, Fig. 11). Asioryctes modified from Carroll (1988, Fig. 20-3b). Abbreviations: ag = angular; ar = articular; cp = coronoid process; d = dentary; f = lateral temporal fenestra; j = jugal; mm = attachment site for mammalian jaw muscles; o = eye socket; po = post orbital; q = quadrate; rl = reflected lamina; sq = squamosal; ty = tympanic. .

 

 

 

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Are you convinced yet?

 

Oscillating eye sizes,

head shapes that shift back and forth,

teeth that are large, then small, then large again.

 

Yeah; I believe this stuff!

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(The chart is from The Fossil Record: Evolution or "Scientific Creation" by Clifford A. Cuffey. It is on part 5 of a multipart article. The beginning of the article is here.  )

There are some Evo's who think... "It effectively demolishes the entire creationist argument. Excellent reading!"

After seeing these pix; do you?

[muawiyah]

I have a photo of a photo taken of Jesus at the moment of resurrection. So, do either of you really look like Jesus? We can check.