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.
Snow is "ordered" --it consists of millions of perfectly formed 6-sided crystals-- yet it forms from disordered water vapor.
Does it do that "by itself"? That is a philosophical question. It certainly does so according to the laws of nature.
Personally, I believe that God is the ultimate author of the laws of nature. But I don't believe that He sits down and carves each snowflake. I think He created a universe with natural laws and knew that those laws would be sufficient to accomplish His purposes. I therefore see no conflict between my belief in God and my acceptance of the overwhelming evidence for evolution.
That is, that a new paradigm is usually accepted by the younger scientists since they have no shot at the grants going to the older scientists who hold to the older paradigm. (Just in case you needed to be told what the motive is.)
Eventually the old guys pass on to their reward, and there's no one left to argue on behalf of the old paradigm.
Maybe your experience is different.
That is your opinion. Math is used to "describe" physical and non-physical elements, and it is the very foundation of science.
Let's assume they're real ~ as is the vacuum.
FWIW, I've never used the product you recommended. (Couldn't find the "trademark" key on my laptop.) Is it really a great improvement over that cow/bull branded stuff? '-)
Not really. I'm afraid you really have no appreciation of the diversity of thought in the Christian community.
Somebody just tried to remove the very mother of science, to wit, mathematics, from scientific inquiry.
Well off goes opinion again. The father of science as we know it was Aristotle. Descartes is generally thought the father of mathematics. Neither are mothers. Mathemathics and science are not the same and mathematics is not science. Take every mathematics course offered, you will not prove one theory with mathematics. If mathematics were science it would be called science, not mathematics.
"Not really. I'm afraid you really have no appreciation of the diversity of thought in the Christian community."
No, really. Christians believe the Bible to be objectively true, no matter what you wish to believe.
man-up and admit your error - otherwise I really have nothing more to say to you.
The method of Mathematics is designation of symbols and numbers to prove absolutes or determine laws.
The methods are separate and distinct and are not interchangeable."
Posted by jec41 (Screaming Eagle)
Carolinaguitano bought off on that one with his silence.
Certainly God would not be distracted by wasting all His time carving snowflakes ~ which might well explain why they are all different (except for the 2 featured in Science News last year that looked to be identical).
It seems to be your argument that the nature of reality has bearing on the way science plays out.
I could care less.
All in good fun -- but I really would like to know how well the "GG" stuff works...
"You are the one concerned with the existence of objective reality. I'm not."
Obviously.
"It seems to be your argument that the nature of reality has bearing on the way science plays out."
Of course it does.
"I could care less."
No doubt.
Science and mathematics don't assume anything. Assumptions are of philosophy and opinion.
The method of Mathematics is designation of symbols and numbers to prove absolutes or determine laws.
The methods are separate and distinct and are not interchangeable."
Posted by jec41 (Screaming Eagle)
Carolinaguitano bought off on that one with his silence.
This is the post. He opined that science is mathematics.
... what I believe regarding reality, is it objective or subjective, has no bearing on its existence. Reality is allowed to pursue its own future, as am I.
From what I've heard, acid flashbacks are a bitch. If you think you may be experiencing one, I've heard the best thing to do is to just lie down, breath slowly, and try to take a nap.
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