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.
So you found under the gooseberry bush?...I know those who say they were found in the cabbage patch...that cabbage patch 'theory' of where babies come from, must have been a truly popular 'theory', noting the popularity of the Cabbage Patch line of dolls, that made its creator quite rich...
Ah, so many 'theories' of where babies come from...
Apologies, Sun. Yet another demonstration that creationist views are so inane that they are beyond parody. I missed the quotes round VR's humorous mocking retort to you and thought that you were making a point in all seriousness.
What I cannot make out in all of this is whether or not you are really so dunderheaded that you believe that Darwin didn't know that mammals are multi-cellular, when the nature of cells had been common knowledge amongst biologists for hundreds of years before the voyage of the Beagle. In fact reviewing the thread I think the time may now be ripe to call "Loki Troll", or "No Kin to Monkeys".
I accepted Evolution when I accepted change? NO, I did not. Change is not evolution.
Sorry about your dads accident. Hope he is doing well.
Evolution is defined as ongoing change. Darwin did not use the term evolution. He used the terms change and differences. Evolution is a later term to include both. Evolution is defined as ongoing change. Change and differences (evolution) are the facts that Darwin observed.
Web Definition; In the life sciences, evolution is a change in the traits of living organisms over generations, including the emergence of new species. Since the development of modern genetics in the 1940s, evolution has been defined more specifically as a change in the frequency of alleles in a population from one generation to the next. In other fields evolution is used more generally to refer to any process of change over time.
I suggest you reread Darwin' Origin of the Species.
I always assumed that there was some limit on how much retardation someone could exhibit, yet still manage to operate a computer sufficiently to post on a website. Now I'm starting to wonder.
I thought we were doing rather well.
It appears that the Gooseberry Bush schtick betrays my Limey origins.
What a really great, humorous link, explaining where babies come from...my favorite, and its probably true for me and the hubby...Babies?..."They're found in beer"....me and the hubby have a special extra-cirriculur activity that we enjoy quite a bit...sampling beer from all the various micro-breweries here in the Pacific Northwest...tho we have grown cabbages, we prefer to drink beer...
Some of those 'theories' of where babies come from are hysterical...thanks for providing me with my good hearty laugh of the day...
One of the many problems HUMAN beings must deal with is that at no time is it possible for us the know "what something IS'.
We can only characterize. We cannot define the totality of anything.
We can only compare what we know of one thing to another thing.
When God Says "Let there be Light".
We automatically think He was speaking of the sun.
He said LIGHT.
We still do not know what LIGHT is.
Does that mean God Lied???
God knows everthing completely. When He speaks of the totality of something we have no way to Compare His statement to anything else we know.
Jesus said, "I am the Truth......"
We have been asking the same question since Pilot asked it. Are we closer to an answer or do we just say, "He lied"?
I would be most careful when claiming God "Lied". You and I don't know the whole story YET. We must still compare.
That is why science only deals with physical evidence and empirical methods. Following the evidence has been very useful for several centuries. It does not answer moral or theological questions, but it does result in a steady accumulation of knowledge.
Thank you so much for engaging meditations and insights!
Placemarker
More importantly, do you think that Darwin knew that there was TRILLIONS of cells? Of course, he didn't, but did he even believe that there could be hundreds of cells. Nope.
He believed in evolution based on erroneous "facts", and most of the scientists are still believing in that THEORY today.
It's sad that students are wasting their time with this antiquated theory.
"More importantly, do you think that Darwin knew that there was TRILLIONS of cells? Of course, he didn't, but did he even believe that there could be hundreds of cells. Nope."
Are you saying that Darwin thought the body was made of one big cell? Or are you saying that Darwin didn't know of the 200-300 different types of cells that make up the body?
You have been less than clear on this.
So what? The theory of eovlution does not require the existence of cells. It requires heritability, variability, and natural selection.
By the way, are you going to acknowledge you misrepresented that webpage?
Misrepresenting implies conscious intent. We have been tweaking Mr. Sun for a while, and I honestly don't think he is capable of understanding the problem. Perhaps English is not his first language.
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