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.
In Darwinian evolution, the source of variation is irrelevant. Selection will, in the long run, determine the shape of species, even those that have been manipulated by humans.
Clearly, it would have been wasted on you. Perhaps that has to do with your fundamental misunderstanding of the way in which scientists use the word "theory."
When you have some time, I'd still like to see your rendition of the Theory of Evolution. As you have been so vocal in your opposition to it, you must be quite familiar with it.
It isn't often I can use a single piece to bring together communism, fascism, Islam and gnosticism, but there it is.
All of them assume it is possible to know all the truth, and here it is on this plate ~ take it.
Sorry ~ God, and "reality", continue to provide revelation of new things, new systems, new approaches to new questions or old, settled issues.
Notice that Islam argues that Mohammad was the LAST PROPHET and there will be no more revelations. Marx and the fascist theoreticians argued that there was an endpoint to Hegelian logic, and they knew what that endpoint was ~ no more thesis/antithesis.
Gnosticism argues that we can "know" with objective certainty.
Sorry ~ doesn't work that way ~ it's quite subjective all the way down, and new stuff just keeps popping up all the time. Today there's news of two supermassive blackholes in a distant galaxy preparing to collide. Billions of stars will be sucked into the new super-supermassive blackhole.
Maybe.
Still, we know this happened hundreds of millions of years ago.
Again, the demigod "Natural Selection" steps in. Fortunately this allpowerful figure seems to have little effect on the HOX genes eh?! Else we might have 3 eyes and 6 legs from time to time, and you can't say that system doesn't have some competitive advantages.
Also, it is collEge not collAge....:) LOL!
No hard feelings I hope, debating is supposed to be fun.
Competetitive advantage is definded by which individuals produce the most offspring.
Not which "produce", but which "have survive".
As you note -- "There are climatic types that are named after these zones."
BTW, we are now engaged in a contest to see whether it's going to be the bird flu or people who kill the most birds this year.
Survive and reproduce. At any rate, this is why a discussion of evolution only makes sense in the context of populations, and should not be applied to individuals.
"Are you trying to say that Christianity does teach absolutes?"
That should be *doesn't*.
True, there are some people who might argue that, but they're the ones who would deny God the privilege of further revelation.
The God of the Universe really can't be capped.
BTW, the commies and fascists believe their reality is an "objective reality" whether you do or not.
CG: Nonsense. Nobody is saying that an intelligent designer doesn't exist (man). That in NO way is evidence that Man is the intelligent designer of the universe. There is simply no evidence for a designer of the universe, or of life as we see it on Earth, that isn't easier explained with natural means.
M: He doesn't have to create the Universe ~ just one new lifeform is sufficient, and it doesn't even have to be all that different ...
This appears to be Fester's oft-stated (and oft-denied) formulation that anything anywhere intelligently designed by anyone is evidence that everything everywhere was intelligently designed.
Fester tells me that's not what he means, but his posts can be somewhat murky. Mmuawiyah, on the other hand, seems to mean exactly that. Perhaps they can get together and sort it out for us.
I know. I suppose it makes them feel superior.
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