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.
Knock off the personal attacks!
No, that was the snakehead.
Does this suggest that man evolved from modern chimpanzee?
No. The exact line of descent is still being worked out, but it is certainly not from modern chimpanzees. (Chimpanzees have evolved a little also, but forest fossils are pretty difficult to find. Genetics are probably a better field to use for these relationships, much as I love bones.)
So how many species are there? 6.7 million just of humans alone? If every single individual of plant, animal, or insect is considered a species because it is different form every other kind, then the Tree of Life needs some major correction; especially everytime something is born or dies. So how is *species* defined? Who gets to decide where to draw the line? If any change is evolutiion, then we should see new species arising regularly. Where are they? Just out of curiosity, what was the last known change from one species to another and when and where did it occur?
Gotcha.
Just seemed a bit odd to be listed there. Not picking a fight.
Ah, so, of course, you 99% of the scientists would be willing to stipulate to an intelligent designer as well as anything, as the genisis of life on Earth, then.
He can't get more specific than *blurs*? The statement that humans evolved form something similar is a pretty safe one for an evolutionist to make, very non-commital and certainly not new. There is nothing in the article, however, that states *This is it*. It sounds like wishful thinking on his part.
"There is no need for that proposition. Except for Occam's Razor."
Occam's razor helps my side, not yours.
But, to have gone from the simplest one celled form to a very complex form, "different but not more" understates the reality, wouldn't you agree?
My browser crashed in the middle of my reply, remind me to freepmail you sometime during the next week over this...
Cheers!
Ok, not that I really ever like getting into to this, but evolution is ABSOLUTELY NOT AN OBSERVED FACT.
Paleontologists have studied different fauna and flora from different aged stratas, found different fossil remains, and have made INFERENCES as to the relation of the observed fossil finds. NO ONE, unless thay are millions of years old, can have actually observed evolution. but if you believe in evolution, that could not have happened either because you would now be extinct.
The contention by the scientist that he brought up is a good one. There's way too much speculation in some of the things that guy said. Where's the evidence to back up the claim that predators were the cause ofthis creatures apparently moving to land. Pretty high level of reasoning ability demonstrated by that creature there. It's as bad as the comment I heard on a show about cheetahs that explained that the cheetahs left their previous region to avoid an outbreak of anthrax. Sheesh. Where do these people come up with this stuff?
(Whispered murmurs: "How does he do that?")
Take a bow, Radio.
Cheers!
No, that is the vietnamese snakefish (which tastes good, a delicacy in SE Asia). The lungfish can be bought for a personal aquarium, but leave space at the top, even though it is a fish, it breathes air from the surface to live. A fascinating species.
Those species that have so changed they can't reproduce.
Evolution is defined as on going change or a fact. A theory explains the fact. I don't know the last new species , they occur every day. Goggle up new species, you will find many. Just out of curiosity, what was the last Creation or Intelligent Designer that you observed as a material fact?
Just seemed a bit odd to be listed there. Not picking a fight.
Nor did I interpret it as such. It was a civil question.
I suspect the Smithsonian folks who put the picture together put modern chimpanzee at one end and modern humans at the other as an illustrative device.
There is a terrible lack of fossils from the forests in the 5-10 mya year range. Only when critters headed for the grasslands did we start getting a better fossil record.
I'm out for the night.
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