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.
No I don't remember and I'm really sorry to be arguing about something I can't even remember. It was on Animal Planet's "Most Extreme Animals" a few nights ago. We always watch that at 7 PM with our 7 year old. I'll research it later. I'm truly not delirious, LOL. This episode got me to thinking about the whole evolution thing. It was really interesting in that regard. I'll ping you later if I find something.
Yes. Just like birds nowadays.
No, evolutionists have never said this. No wonder you think the theory of evolution is so improbable if you think that's what we think!
Dunno. However, many of the fundamentalists of my acquaintance consider the KJV to be the most accurate English translation. The translators used the word "repent" for a reason.
Are you suggesting that evidence exists that the techniques used in current genetic engineering methods were employed in th e past, despite no evidence of any species existing with the intellect or physical capabilities of using such methods?
Due to modern discoveries in breeding that enabled researchers to move genes from one species of plant to another, there was some softening of this point. After all, it was beginning to look like plants were just one big ol' species with no boundaries, and no one wanted to deal with that.
Last week's Science News carried an article about even later research that indicates there are fixed boundaries to plant species, just like there are for animal species.
Consequently, it's safe to go back to the older standard and abandon the equivocation and cant.
Bacteria and archaeobacter have a different problem. Many bacteria of quite different species seem to be able to use conjugation to pass on beneficial genes to each other (presumably for immunological purposes, or maybe they're just into mysticism). Still there are species boundaries for bacteria, and no one has seems to have observed the creation of a new species lately ~ if ever, although they are all the time discovering new ones.
Now, what might the speciation among viruses mean? No doubt they evolve, but do viruses have species boundaries?
Again, mere change is not evidence of the original Darwinian claims for evolution. Else, we are all little different than the Creationist who accept breeding dogs for various traits, but reject the idea that such change might well end up with something other than a dog.
Just one new species ~ do it.
Can't get classier than Nature.
If the vast array of species of plant, animal and insect here today were to have come into being by blind chance through a precess of evolution, you either have to start at some point with no life at all, or explain the origin of the proto-life.
Which would you choose? 
True, but all change between generations is minor. Always. There is never a case in which a child is a new species from the parent. Never.
Lungfish are not part of the chain. The differentiation began before today's lungfish came along.
Since species transitions typically take thousands of years minimum, and changes on the order of what creationists would like to see demonstrated may take much much longer, these events don't take place on a time scale short enough for direct observation.
There are examples of populations that are diverging in an incipient speciation event. Two examples I've read about recently are with a species of frog and a species of abalone.
That should be *through* not *though*.
Yeah...that's definitely a transition of some kind. LOL.
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