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.

###

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.

[atlaw]

The fossil record should be be composed almost entirely of transitional forms. It isn't.

How do you define transitional form? In other words, can you describe what you believe a transitional form would look like?

[Zavien Doombringer]

what is the "true" way to join two boards together at right angles?

The truth would be that the two boards can be joined, not in the how.

[Fester Chugabrew]

The principal of parsimony has not been empirically tested as a valid means of attaining objective knowlegde. IOW, the simplest explanation is not necessarily the truest one. Creationists have been accused of stifling scientific inquiry because they attribute the general organization and behavior of matter to an intelligent designer. In fact, it is evolutionists who throw up their hands and say "We don't know, and what cannot know, what is behind this mere 'appearance' of organization."

[dread78645]

Not sure why that applies to cows ~ that's why Jews eschew the consumption of cheeseburgers.

It's the mixing of milchig and fleishig.
Milk represents birth and life sustenance. The flesh stands for corruption and death.

McDonald's founder Ray Kroc mentions running into a Florida health ordinance that prohibited milkshakes and hamburgers from being prepared in the same room. In order to pass inspection, they ended up having to put the Mixmaster in a plexiglas 'booth'.
That upset Ray's carefully planned 'service ballet' that he was so proud of.

[William Terrell]

How does changing information in a database make the database more complex? How does a database become more complex if a copy of it is made? How does it become more complex if, following a copy, some records are changed?

Changes to a table in a database makes the record interaction with other tables more complex. If a copy is made, corruption of data is possible making it complex beyond use. See the first sentence.

Simplicity and complexity are dependent on the fixed program that processes it. Trans-species evolution depends on the process by which organisms survive, in other words, the programs that processes their ability to survive.

However, a database implies an intelligent creator. What does the set of laws and processes that would allow "survival of the fittest", in the context of moving from a one celled animals to a more complex organisms, imply?

[Quark2005]

No, but you have to have sufficient evidence that doesn't admit of more than one interpretation.

We do. Fossil evidence combined with biogeographical evidence, morphological evidence, and vast amounts of genetic evidence (the strongest of all) points to only one interpretation with consistent results: evolution.

The fossil record should be be composed almost entirely of transitional forms. It isn't.

It is. There are thousands of examples of transitional fossils. Every fossil that doesn't represent a lineage that immediately became extinct is a transitional form. And even representations of lineages that became extinct provide insight into closely related lineages that existed at around the same time.

Every single bit of evidence you have requires a presupposition of trans-species evolution.

Nope. Not when fossil evidence is cross-referenced with evidence from the other completely independent lines of inquiry I mentioned, all of which point to the same result: evolution. The result of several lines of inquiry painting a consistent picture of a theory is known as consilience, and is the primary means by which almost all scientific theories are given credence.

You have to know something for sure, and you don't.

We know a lot more about evolution than you think. Learn it or get left behind.

[King Prout]

No, scientists accept new models only through a process of attribiton where the old believers die off and are replaced with the new believers.

"only" is a big word, kid. like all absolute qualifiers, it is one requiring but a single counterexample to refute.

I am not one of the big dogs on the history of science in the 20th century, so I cannot easily give you one clear example of a scientist accepting a new model after strongly supporting an old one. However: I know there have been not one but many such, and am quite certain one of the big dogs I have included as recipients of this note can easily provide names of such examples.

What I don't know is whether:
1. they will consider it worth doing, or
2. whether you are capable of accepting a factual rebuttal.

[King Prout]

ant you meant "attrition" not "attribution" when you typed "attribiton", yes?

[Fester Chugabrew]

I do not question the existence of objective reality, nor do I question that certain parts of objective reality are accessible to human reason. But I do question my capacities as an observer. You and your evo buddies have it all figured out, and apparently remain convinced in your own minds that you are wholly without biases that would color your interpretation of the evidence.

Me? I can look at reality both ways: as a product of intelligent design or as a product of unguided forces of nature. I can even understand why both considerations ought to be allowed in school (perhaps not under the guise of science). You? You're afraid of the idea of an intelligent designer to the point you would invoke the law of the land to see to it that your subjective basis and assumptions reign supreme in the schools. I have been taught to despise tyranny of all kinds, and that includes the intellectual tyranny of evolutionary dogma.

[William Terrell]

Useless to further discuss this. Tired of arguing. Macro-evolution doesn't impress me. It lacks the ring of truth even without its lack of evidence, which is why the debate wasn't ended long ago.

Another time.

[js1138]

So you are saying that a database whose records are duplicated has significantly more information than one that doesn't? I wonder what Shannon would say about that?

[William Terrell]

Useless to further discuss this. Tired of arguing. Macro-evolution doesn't impress me. It lacks the ring of truth even without its lack of evidence, which is why the debate wasn't ended long ago.

Another time.

[William Terrell]

Useless to further discuss this. Tired of arguing. Macro-evolution doesn't impress me. It lacks the ring of truth even without its lack of evidence, which is why the debate wasn't ended long ago.

Another time.

[William Terrell]

Useless to further discuss this. Tired of arguing. Macro-evolution doesn't impress me. It lacks the ring of truth even without its lack of evidence, which is why the debate wasn't ended long ago.

Another time.

[js1138]

Selection is not random.

[CarolinaGuitarman]

"I do not question the existence of objective reality, nor do I question that certain parts of objective reality are accessible to human reason."

Ok.

"But I do question my capacities as an observer."

Ok.

"You and your evo buddies have it all figured out, and apparently remain convinced in your own minds that you are wholly without biases that would color your interpretation of the evidence."

No, but as I live in a world where I need to make decisions based on imperfect data, I look for methods that will give me the best chance of making the correct decision. That method is science.

"Me? I can look at reality both ways: as a product of intelligent design or as a product of unguided forces of nature."

"You? You're afraid of the idea of an intelligent designer to the point you would invoke the law of the land to see to it that your subjective basis and assumptions reign supreme in the schools."

You have it a%^-backwards. You want the law of the land to recognize your clearly subjective claim (ID).

" I have been taught to despise tyranny of all kinds, and that includes the intellectual tyranny of evolutionary dogma."

Science is not tyranny. Subjective/post-modernism will lead to tyranny though.

[Quark2005]

Macro-evolution doesn't impress me. It lacks the ring of truth even without its lack of evidence, which is why the debate wasn't ended long ago.

The real debate has ended a long time ago. Scientists (so-named because they actually understand science) almost 100% unanimously accept the theory of evolution on its strong merits, and have for many decades. The fact that the debate persists in the general public only makes a statement about the pervasive and unsettling lack of understanding of science among the general population.

[atlaw]

Like the introduction of a aimless random force that bring organization from disorder?

What "aimless force"? The aimless force underlying hurricanes? Or salt crystallization? Or formation of oil droplets on water? Or any biological mass accumulation (from human growth to tree growth to red tides)? Or self-assembled island growth in highly-mismatched semiconductor heterostructures?

Or do these occurrences too require for an explanation the introduction of a supernatural agency?

I'm sorry, but "turtles all the way down" is not synonymous with Occam's Razor.

[TXnMA]

...what is the "true" way to join two boards together at right angles?

Interesting point!

The "true way" is that which results in the final position of the boards being at exactly 90 degrees (at right angles) to each other. The "truth" is in the observable result ("at right angles -- as specified"). Nothing need be said about the method -- or "process" -- to make the statement "true".

Indeed, in Genesis, the Creator said next to nothing about the processes He used; all He mentioned was the truth of the results. ("And God said, "Let there be light.")

As a scientist and a Christian, I am greatly offended by simpleminded and dogmatic "Creationists" (yes, I am talking about you!) who insist that they can dictate the process (and timescale) of creation based on a scriptural "outline" that does not describe process. Even mor offensive is their penchant for "dissing" the works of anyone who uses their Creator-given intellect to try to "fill in the blanks" with understanding of how the Universe has reached its present state.

OTOH, I am similarly offended by "scientific observers" who ignore the truth of Scripture, ("God created the heavens and the earth".) and who insist that their speculations (theories) as to how the Universe developed alone constitute "truth".

Neither have a corner on "truth" -- especially those who stake their "faith" on medieval-minded misinterpretation of a 1611 multi-mis-translation and who sneer at others who rejoice in the revealed truths of actual observation.

...listening for the "hit dogs" to whine... ;-}

[Lurking Libertarian]

after reading the reports of new species listed mainly plants and fly..Any intelligent person would laugh. a fly is a fly, a maze is a maze.

You are confusing species with genus with order with phylum, etc., etc. If two types of fish cannot interbreed, they are different species. They are both "fish," in the same way that wolves, dogs and coyotes are all "canines" and that humans, chimpanzees and gorillas are all "primates," but they are indisputably different species. Because they cannot interbreed, any genetic change that happens in one species cannot possibly spread to the other, and therefore, over time, the differences between them will only grow greater.

when you show a true change from fish to mammal well then your hypothesis that evolution is leading to new species could hold water , otherwise birds that cannot interbreed are still birds, not fish. no?

You are mistaken as to what the theory of evolution predicts. No scientist who accepts evolution ever predicted that a fish would become a mammal in one generation or even in a thousand generations. Evolution works in small steps, which eventually lead to new species (something we have observed in the wild and in the lab) which eventually (over tens of thousands, or even millions, of years) produces entirely new types of creatures.