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.

[mlc9852]

They do need to get their herders straight!

[CarolinaGuitarman]

They both are epistemological subjectivists/relativists too.

As I told them, post-modernism isn't my bag.

[MeanWestTexan]

"You didn't post that really did you..how many movies such as the lord of the Rings have computer generated motion???"

So you believe fossils were planted by God or the Enemy to give a false sense of evolution?

That is certainly an unrefutable belief, and you could be correct.

[Quark2005]

These are the first instances of SHEEP and GOAT I could find.

Exodus 23:19: Do not cook a young goat in its mother's milk.

Finally, information I can use!!! :^)

[William Terrell]

The laws of nature aren't random. Chemical reactions are not random. Natural selection isn't random. Your premises are all faulty.

Laws imply a law giver or maker. You have random or you have purpose. Purpose implies an intelligent force.

You appear confused. Trans-species evolution is untestable, also.

Occam's Razor demands that the simplest explanation be accepted. You have, on one side, an intelligent force behind the interactive, precise structure of living forms, or unguided random causes.

Since the reflection of these systems would imply an intelligent cause to a reasonable person observing the result, the simplest explanation is that it was created and guided. You have to duck and weave with opaque reasoning, and presuppose the conclusion otherwise, making the explanation contrived and complex.

[William Terrell]

There are those who accept evolution and believe that no intelligence is behind the origin of life, however that does not make such a belief part of the theory of evolution, nor does that make such a belief a scientific theory itself.

Yes? And who might those be who think evolution is guided by intelligent design? The teaching of evolution is used for the point of being able to state that the world exists without a creator. That has been so stated by all the "fathers" of evolution.

If you object to that use, fell free to criticize them.

[jec41]

Well your pseudofundimental/religion has not proved any observable facts to the contrary. Science has provided both facts and evidence for evolution. The most that you have provided is opinion. If you want to prove science wrong do so. Learn the scientific method. Learn how to determine a observable fact and whats required. Learn the difference between empirical evidence and evidence. Learn the difference between evolution and the theory of evolution. Learn the difference between the philosophical method and the scientific method. Learn why math is not science. Your accusations have been presented and refuted time and time again on these threads but you still offer only opinion and refuse any evidence. If you want to see new species just google up new species and read 500 articles. Science does not observe faith and belief but only material facts. Refute the facts with evidence and provide new material facts by your faith and belief.

[CarolinaGuitarman]

" Laws imply a law giver or maker."

No, they really don't. A better term would be *regularity* at any rate.

" You have random or you have purpose. Purpose implies an intelligent force."

No, you have random and you have order.

" You appear confused. Trans-species evolution is untestable, also."

Not only is it testable, it has been observed.

" Occam's Razor demands that the simplest explanation be accepted."

Actually, it demands that the simplest explanation that fits the facts should be accepted. ID fits every conceivable fact. It is an unnecessary proposition.

"You have, on one side, an intelligent force behind the interactive, precise structure of living forms, or unguided random causes."

No, you have regularities that we call laws.

"Since the reflection of these systems would imply an intelligent cause to a reasonable person observing the result, the simplest explanation is that it was created and guided."

The simplest conclusion is that natural processes are responsible for what we see. ID is an untestable addition that adds nothing to our understanding of the universe, but instead places a stop-sign on further research because if you say that *God did it*, what else is there to know?

"You have to duck and weave with opaque reasoning, and presuppose the conclusion otherwise, making the explanation contrived and complex."

True, ID does have many logical flaws.

[William Terrell]

Duck and weave.

[jec41]

Again, another reader simply doesn't believe Darwin ever had sex ~ and certainly not with his wife. He still ended up with 10 kids.

What does your illogical conclusion have to do with anything other than a agenda of opinion by accusation and smear.

[William Terrell]

For basic elements to eventually end in the vast diversity of plant, animal and insect life today by random action, you have to, at some point, have life come from nonlife, or the theory collapses.

The moment you presuppose life and start from there, to avoid an intelligent creator, you must explain how that life came into being. You try to avoid this corundum by stating that the theory doesn't need to address that.

It absolutely does. I'm not impressed so far.

[William Terrell]

How do you measure complexity or information content?

Is a frog more complex that a bacterium?

[Dimensio]

Duck and weave.

This does not falsify my statement. Demonstrating that humans can genetically modify or even create life does not provide evidence of an entity or entities doing the same thing 4.6 billion years ago.

[Dimensio]

Laws imply a law giver or maker.

This is a semantic argument, using a truth behind one definition of "law" to make a claim about a different definition. This is not a valid line of reasoning.

[Dimensio]

And who might those be who think evolution is guided by intelligent design?

There are individuals here on FreeRepublic who have stated such. Michael Behe also believes this, however he believes that the intelligent designer's intervention is more overt and detectable.

The teaching of evolution is used for the point of being able to state that the world exists without a creator.

By whom? Please be specific, explaining exactly how the theory of evolution is used to justify the premise that the world exists without a creator.

That has been so stated by all the "fathers" of evolution.

Please provide citations from the "fathers" where they explain how the theory of evolution demonstrates that the world exists without a creator.

[aNYCguy]

ydh: There is that word again [theory]. Evolution is just someone's idea, not a fact.

Condorman: By your logic Music Theory means that music is "just someone's idea" and it must not exist.

ydh: I avoided that class in college because I refused to waste my money on it, which is what I think it is, a bunch of bologna.

I notice that in your rush to declare your ignorance of music theory, you completely avoided responding to Condorman's point, which is that by your absurd understanding of the word "theory," music is just someone's idea and has not been proved to exist. Any plan to respond?

[jec41]

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.

I did not substitute anything. It has been defined as such for 100's of years. It will not be redefined by you whether you can compute or not.

[js1138]

Is a frog more complex that a bacterium?

Again, how do you wish to define complexity? At some point in the life cycle, both the frog and the bacterium are single celled. Most bacteria have smaller genomes, but genome length does not correlate perfectly with presumed complexity or position on the phylogenetic tree.

So once again, why do anti-evolutionists assume that evolution involves an increase in information or complexity?

[js1138]

Is a frog more complex that a bacterium?

Does a database become more complex when you change the data? Does it become significantly more complex if you duplicate all the records? Does it become significantly more complex if, after the record duplication, some records are changed?

How do you measure complexity in living things?

[Quark2005]

The moment you presuppose life and start from there, to avoid an intelligent creator, you must explain how that life came into being. You try to avoid this corundum by stating that the theory doesn't need to address that.

1) Do you have factual information about who your great grandparents were?

2) Do you have a complete understanding of the origins of all life on earth?

3) Do you likewise think it's possible that we know something about the ancestry of life on earth without knowing everything about how it originated?

This ain't too hard to grasp, folks.