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.
That is not true. We simply recognize the impossibility of reaching any certain conclusion as to whether there are no god, many gods, some gods, one goddess, demi-gods, etc. Anyone who says they are certain is simply emoting.
Which "church"? After all, some "churches" are founded on the idea that we are, as it were, the imaginings or thoughts of a sleeper who is awakening.
OTOH, I am similarly offended by "scientific observers" who ignore the truth of Scripture, ("God created the heavens and the earth".) and who insist that their speculations (theories) as to how the Universe developed alone constitute "truth".
Neither have a corner on "truth" ...
Their only hope is to realize they are in fact blind - and what they observe is strictly a matter of their approach (leg, ear, trunk). Then perhaps they can quit the pointless recriminations and actually make some progress...
Mistakes were made.
I thought you were an atheist. At least they have made some kind of decision.
Alfred Weggener was laughed off the stage at his first presentation of his continental drift theory. Not a scientist of his age ever adopted the Weggenerian view.
Eventually, the new science of tectonics proved Weggener to be correct. All current scientists believe tectonics to be the correct answer.
At the same time all the unbelievers are now conveniently dead.
CTM (Critical Troll Mass) achieved placemarker
Yes, attrition. They die off in fact.
Definitions of evolution on the Web:
development: a process in which something passes by degrees to a different stage (especially a more advanced or mature stage); "the development of his ideas took many years"; "the evolution of Greek civilization"; "the slow development of her skill as a writer"
(biology) the sequence of events involved in the evolutionary development of a species or taxonomic group of organisms
wordnet.princeton.edu/perl/webwn
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.
en.wikipedia.org/wiki/Evolution
Interesting story. I think most of us have experienced occurrences or feelings we can't logically explain. None of it meets any scientific criteria, of course, but "man does not live on bread alone," though, I'll be the first to admit.
We now know gradualism doesn't work ~ tectonics work!
I detect a thread of "gradualism" in the posts from the Evos here ~ time to catch up to DNA though. The dynamics there simply do not require "gradualism". In fact, we can go in and change the whole picture ourselves. Over the long run we will probably take charge of our own and other genomes.
That's going to really pi$$ off the Creos too.
1. Can you prove that doubled-absolute assertion?
2. Would you be willing to admit that a single counterexample invaldates such an absolute assertion?
Have you looked into what's going on with the development of new bio-fuels? They (ADM, et al) are planning on inserting instructions in the genome for various plants that will create an enzyme that turns all the cellulose into alcohol when it is heated.
Evolution as we knew it IS OVER.
There goes the nieghborhood!
"We now know gradualism doesn't work ~ tectonics work!"
Plate tectonics is a gradual process.
Are you trying to say that mutations don't start in a mere individual??
But you steal a base, here. You use "truth of Scripture" like its an objectively proved fact. It isn't. In fact, given the historic propensity for humans to create religions, sects, cults, etc., and given that the content of no religion's scriptures can even begin to be demonstrably true, the phrase, "truth of Scripture" can objectively be termed an oxymoron.
There is no "truth" in any scripture, but simply the subjective emotions of its adherents.
BTW, my statement is correct whether we are talking about "defined" or "hundreds".
You have already said that the universe may be in your head. Solipsism. so you may have your own definition of evolution. However the world of science does not operate in your head and accepts the following definition of evolution that science determined.
ev·o·lu·tion (v-lshn, v-)
n.
1. A continuing process of change from one state or condition to another or from one form to another. 2. The theory that groups of organisms change with passage of time, mainly as a result of natural selection, so that descendants differ morphologically and physiologically from their ancestors.
The American Heritage® Stedman's Medical Dictionary, 2nd Edition Copyright © 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
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