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.
Really? According to the Bible, God Himself admitted to making a mistake right before he Flooded the world.
Thank you, I've been around for a while although I have not requested a ping. Ichneumon overwhelms them because they do not understand his level of competence. I try to give a simple example they can't refute. Remember our high school graduates are now only 24th in the top 25 countries in math and science. They are first in self esteem. Their opinion has become more valuable to them than knowledge.
"and cloning does what?"
Makes an exact copy.
"Meaning that the clone is not an individual, yet a likeness of the host?"
Meaning its genome is not unique.
" Then you cannot make a true clone, due to the fact that by age, clones are not alike either."
True. Your point? I was not the one who claimed to be a clone; that was you. :)
And it repented the LORD that he had made man on the earth, and it grieved him at his heart. And the LORD said, I will destroy man whom I have created from the face of the earth; both man, and beast, and the creeping thing, and the fowls of the air; for it repenteth me that I have made them. [Gen 6:6-7]
Psst...I am female.
I read that differently. But to each his/her own.
What is the biological mechanism that transforms the lobe-finned fish into the tetrapod?
Oh puleeeze...it is a load of crap, IMHO. Please know that I understand some people disagree with me on that, you included, but I will not make 3rd grade comments about your IQ, etc... you lose the argument once you do that.
I can't tell you the incongruity in your characterization of your creation. Of course, who am I to question God's will? God may have wanted to create an obnoxious ignoramus to heckle science from a seat on an upended crate.
We will just have to agree to disagree.
Then what's this then?
Still waiting on someone to explain the complexity of the cell to me or "molecular machinery". Nothing in Darwin's "THEORY" accounts for the complexity of the cell.
This thread is about how the "no transitional fossils" mantra you guys chant is false. Now, all your other mantras are dishonest, too, but even if one or two weren't it wouldn't give you a license to lie about anything else, would it?
Point One: Complexity can evolve.
Point Two: Molecular evidence overwhelmingly supports evolution.
So, in summary, the "no-transitional fossils" mantra is a lie, and all your other mantras are lies.
No, they are philosophers of theology. They argue faith and belief.
So is gravity, ignore it at your peril.
So9
Please post Darwin's theory so we can see for ourselves.
I owe you two apologies then. One for calling you "he"; and one for mistaking you for the other poster on this thread who is ignorantly asserting that he (or she?) is a clone.
Sorry!
Didn't mean to get under your skin so badly. Good day.
The picture is no doubt a Peppered Moth evo fake of the most egregious kind, as no mudskipper ever climbed a stump like that.
It's the Creationists who are desperate - desperate to come up with another spin on how to ignore another scientific discovery that doesn't fit in with their pre-conceived ideas.
I'll ask Creationists once again to explain the hundreds of different breeds of dogs. If God created every form of life exactly how it is now - then how did mankind breed different types of dogs? And if men can do it - why would you not think Nature can do the same thing?
I was hoping for something better from you. Don't you have someplace else to be????
Apology accepted. I understand how it can happen.
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