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Author Topic:   Fossil Fish (named "Tiktaalik") Sheds Light on Transition
roxrkool
Member (Idle past 1067 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 1 of 42 (301205)
04-05-2006 3:19 PM


Fossil Fish Sheds Light on Transition
By MALCOLM RITTER, AP Science Writer 2 hours, 14 minutes ago
NEW YORK - Scientists have caught a fossil fish in the act of adapting toward a life on land, a discovery that sheds new light one of the greatest transformations in the history of animals.
Scientists have long known that fish evolved into the first creatures on land with four legs and backbones more than 365 million years ago, but they've had precious little fossil evidence to document how it happened.
The new find of several specimens looks more like a land-dweller than the few other fossil fish known from the transitional period, and researchers speculate that it may have taken brief excursions out of the water.
"It sort of blurs the distinction between fish and land-living animals," said one of its discoverers, paleontologist Neil Shubin of the University of Chicago.
Experts said the discovery, with its unusually well-preserved and complete skeletons, reveals significant new information about how the water-to-land evolution took place.
"It's an important new contribution to (understanding) a very, very important transition in the history of life," said Robert Carroll of McGill University in Montreal.
The new find includes specimens, 4 to 9 feet long, found on Ellesmere Island, which lies north of the Arctic Circle in Canada. It is reported in Thursday's issue of the journal Nature by Shubin, Ted Daeschler of the Academy of Natural Sciences in Philadelphia and Farish A. Jenkins Jr. of Harvard.
Some 375 million years ago, the creature looked like a cross between a fish and a crocodile. It swam in shallow, gently meandering streams in what was then a subtropical climate, researchers say. A meat-eater, it lived mostly in water.
Yet, its front fins had bones that correspond to a shoulder, upper arm, elbow, forearm and a primitive version of a wrist, Shubin said. From the shoulder to the wrist area, "it basically looks like a scale-covered arm," he said.
"Here's a creature that has a fin that can do push-ups," he said. "This is clearly an animal that is able to support itself on the ground," probably both in very shallow water and for brief excursions on dry land. On land, it apparently moved like a seal, he said.
It might have pulled itself onto stream banks, perhaps moving from one wet area to another, and even crawled across logs in swamps, said Daeschler.
The researchers have not yet dug up any remains from the hind end of the creature's body, so they don't know exactly what the hind fins and tail might have looked like.
The creature was dubbed Tiktaalik (pronounced "tic-TAH-lick") roseae, and also had the crocodile-shaped head of early amphibians, with eyes on the top rather than the side. Unlike other fish, it could move its head independently of its shoulders like a land animal. The back of its head also had features like those of land-dwellers. It probably had lungs as well as gills, and it had overlapping ribs that could be used to support the body against gravity, Shubin said.
Yet, the creature's jaws and snout were still very fishlike, showing that "evolution proceeds slowly; it proceeds in a mosaic pattern with some elements changing while others stay the same," Daeschler said.
If one considers adaptation as a process of collecting tools to live in a new environment, the new finding offers "a snapshot of the toolkit at this particular point in this evolutionary transition," Daeschler said.
In fact, much of its value comes from this insight into the order in which those tools appeared in fish, said Jennifer Clack of Cambridge University, an expert unconnected with the study.
Knowing that detail about the transition from fish to land-dweller, she said, "might help us to unravel why it happened at all. Why did creatures come out of the water and get legs and walk away?"
It's impossible to tell if Tiktaalik was a direct ancestor of land vertebrates, she said, but if a scientist set out to design a plausible candidate, "you'd probably come up with something like this."
Shubin said the researchers plan to return to the small rocky outcropping that yielded the fossils and recover more material. "We've really only begun to sort of crack that spot," he said.
The site is in Nunavut Territory, and "Tiktaalik" in the creature's name comes from the traditional language used in the area. It refers to a large freshwater fish seen in the shallows.
SOURCE
{Another reference, supplied by Truthlover here - BBC NEWS | Science/Nature | Arctic fossils mark move to land - Adminnemooseus}
{Added the "(named "Tiktaalik")" part to the topic title on 4/22/06. - Adminnemooseus}
This message has been edited by Adminnemooseus, 04-05-2006 06:18 PM
This message has been edited by Adminnemooseus, 04-22-2006 02:19 PM

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Ratel
Inactive Member


Message 2 of 42 (301308)
04-05-2006 6:08 PM
Reply to: Message 1 by roxrkool
04-05-2006 3:19 PM


In anticipation of this new info I went to my local library to see if they carried Nature. Alas, they don't. I guess a university library might carry it? I'd really like to see the fossils and/or drawings of the bones.
Whoops! Nevermind, the Yahoo has some photos. WOW!! I'd hate to be a Creationist today!!!
This message has been edited by Ratel, 04-05-2006 06:15 PM

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Coragyps
Member (Idle past 813 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 3 of 42 (301309)
04-05-2006 6:13 PM
Reply to: Message 2 by Ratel
04-05-2006 6:08 PM


Ratel: Pharyngula has some posted -
Page not found | ScienceBlogs
IIDB has more:
Oops! We ran into some problems. | Internet Infidels Discussion Board
This message has been edited by Coragyps, 04-05-2006 05:16 PM

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Ratel
Inactive Member


Message 4 of 42 (301310)
04-05-2006 6:16 PM
Reply to: Message 3 by Coragyps
04-05-2006 6:13 PM


Thanks, man. This is unbelievable!

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roxrkool
Member (Idle past 1067 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 5 of 42 (301318)
04-05-2006 6:42 PM
Reply to: Message 3 by Coragyps
04-05-2006 6:13 PM


You beat me to it!

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Chiroptera
Inactive Member


Message 6 of 42 (301333)
04-05-2006 7:22 PM
Reply to: Message 2 by Ratel
04-05-2006 6:08 PM


quote:
I'd hate to be a Creationist today!!!
Heh, typical evolutionist. One deformed alligator, and everyone wets their pants.

"Religion is the best business to be in. It's the only one where the customers blame themselves for product failure."
-- Ellis Weiner (quoted on the NAiG message board)

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Ratel
Inactive Member


Message 7 of 42 (301357)
04-05-2006 8:21 PM
Reply to: Message 6 by Chiroptera
04-05-2006 7:22 PM


gatorfish
Ha hah! It really does look like a taxidermist stuck a gator head on a lungfish.

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jar
Member
Posts: 34048
From: Texas!!
Joined: 04-20-2004
Member Rating: 5.7


Message 8 of 42 (301359)
04-05-2006 8:24 PM
Reply to: Message 7 by Ratel
04-05-2006 8:21 PM


Re: gatorfish
More pics from Lancet can be seen here.

Aslan is not a Tame Lion

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RAZD
Member (Idle past 1483 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 9 of 42 (301377)
04-05-2006 9:19 PM
Reply to: Message 5 by roxrkool
04-05-2006 6:42 PM


and you beat me to it.
I was all set to start a thread with this beast ...
Some additional quotes and some comments of mine:
Tiktaalik
Remember that name.
BBC article with pictures
The 383 million-year-old specimens are described as crocodile-like animals with fins instead of limbs that probably lived in shallow water.
Before these finds, palaeontologists knew that lobe-finned fishes evolved into land-living creatures during the Devonian Period.
But fossil records showed a gap between Panderichthys, a fish that lived about 385 million years ago which shows early signs of evolving land-friendly features, and Acanthostega, the earliest known tetrapod (four-limbed land-living animals) dating from about 365 million years ago.
"The really remarkable find came when one of the crew found a snout of a flat-headed animal sticking out of the side of a cliff - that is totally what you want to find because if you are at all lucky the rest of the skeleton is back in the cliff," said Professor Shubin.
The team found three near-complete, well-preserved fossils of the new species, Tiktaalik roseae, in an area of the Arctic called the Nunavut Territory. The largest measures almost 3m (9 ft) in length.
The creature shares some characteristics with a fish; it has fins with webbing, and scales on its back.
But it also has many features in common with land animals. It has a flat crocodile-like head with eyes positioned on top and the beginnings of a neck - something not seen in fish.
"When we look inside the fin, we see a shoulder, we see an elbow, and we see an early version of a wrist, which is very similar to that of all animals that also walk on land," said Professor Shubin.
"Essentially we have an animal that is built to support itself on the ground."
Transitional elements that laid the groundwork for later evolution into land based life - another "missing link" with the transitional elements that evolutionary theory predicted.
Gardian Article, text only
Tiktaalik - the name means "a large, shallow-water fish" in the Inuit language Inuktikuk - shows that the evolution of animals from living in water to living on land happened gradually, with fish first living in shallow water.
The animal lived in the Devonian era lasting from 417m to 354m years ago, and had a skull, neck, and ribs similar to early limbed animals (known as tetrapods), as well as a more primitive jaw, fins, and scales akin to fish.
The near-pristine fossil was found on Ellesmere Island, Canada, which is 600 miles from the north pole in the Arctic Circle.
Scientists from the Academy of Natural Sciences in Philadelphia, the University of Chicago, and Harvard University led several expeditions into the inhospitable icy desert to search for the fossils.
The find is the first complete evidence of an animal that was on the verge of the transition from water to land. "The find is a dream come true," said Ted Daeschler of the Academy of Natural Sciences.
"We knew that the rocks on Ellesmere Island offered a glimpse into the right time period and were formed in the right kinds of environments to provide the potential for finding fossils documenting this important evolutionary transition."
When Tiktaalik lived, the Canadian Arctic region was part of a land mass which straddled the equator. Like the Amazon basin today, it had a subtropical climate and the animal lived in small streams. The skeleton indicates that it could support its body under the force of gravity.
The scientists looked in an area that is inhospitable to most living things today, because they knew that (a) the area dated to the right time in the geological past to be in the transitional period, and (b) at that time it had the right kind of environment for such life - it was not a lucky find in a rock quarry (like Archaeopteryx), but one based on research and prediction, in turn based on previous evidence and evolutionary theory. Where and when, consistent with geology and evolution.
(ibid)
"Most of the major joints of the fin are functional in this fish," Professor 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."
Dr Clack said that, judging from the fossil, the first evolutionary transition from sea to land probably involved learning how to breathe air. "Tiktaalik has lost a series of bones that, in fishes, covers the gill region and helps to operate the gill-breathing mechanism," she said. "The air-breathing mechanism it had would have been elaborated and having lost the series of bones that lies between the head and the shoulder girdle means it's got a neck, it can raise its head more easily in order to gulp the air.
"The flexible robust limbs appear to be connected with pushing the head out of the water to breathe the air."
Perhaps shallow muddy water low in oxygen helped this feature develop.
If you want more information, you may want ot get a copy of Nature Journal or sign up to read these Nature articles (need sign on to read full text). Its on the cover btw.
And Ratel -- you can order a copy.
Enjoy.
ps -- let the dancing spin begin eh?
This message has been edited by RAZD, 04*05*2006 09:22 PM

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roxrkool
Member (Idle past 1067 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 10 of 42 (301476)
04-06-2006 9:40 AM
Reply to: Message 7 by Ratel
04-05-2006 8:21 PM


Re: gatorfish
That occurred to me, too - another piltdown?? LOL

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roxrkool
Member (Idle past 1067 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 11 of 42 (301485)
04-06-2006 9:56 AM
Reply to: Message 9 by RAZD
04-05-2006 9:19 PM


Re: and you beat me to it.
RAZD writes:
The scientists looked in an area that is inhospitable to most living things today, because they knew that (a) the area dated to the right time in the geological past to be in the transitional period, and (b) at that time it had the right kind of environment for such life - it was not a lucky find in a rock quarry (like Archaeopteryx), but one based on research and prediction, in turn based on previous evidence and evolutionary theory. Where and when, consistent with geology and evolution.
I think [the green] is such an important point, R.
This message has been edited by roxrkool, 04-06-2006 09:58 AM

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DBlevins
Member (Idle past 3854 days)
Posts: 652
From: Puyallup, WA.
Joined: 02-04-2003


Message 12 of 42 (301657)
04-06-2006 3:24 PM
Reply to: Message 1 by roxrkool
04-05-2006 3:19 PM


Duane Gish's fishy remark
I thought I'd add a remark on this discovery by one of our favorite creationists, Duane T. Gish:
From the New York Times, Thursday April 6,
"'This alleged transitional fish will have to be evaluated carefully.' But he added that he still found evolution 'questionable because paleontologists have yet to discover any transitional fossils between complex invertebrates and fish, and this destroys the whole evolutionary story.'"

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roxrkool
Member (Idle past 1067 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 13 of 42 (301675)
04-06-2006 3:53 PM
Reply to: Message 12 by DBlevins
04-06-2006 3:24 PM


Re: Duane Gish's fishy remark
What a doof! lol

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Faith 
Suspended Member (Idle past 1522 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 14 of 42 (301723)
04-06-2006 6:06 PM
Reply to: Message 9 by RAZD
04-05-2006 9:19 PM


Re: and you beat me to it.
The scientists looked in an area that is inhospitable to most living things today, because they knew that (a) the area dated to the right time in the geological past to be in the transitional period, and (b) at that time it had the right kind of environment for such life - it was not a lucky find in a rock quarry (like Archaeopteryx), but one based on research and prediction, in turn based on previous evidence and evolutionary theory. Where and when, consistent with geology and evolution.
Translation: They looked where they knew a certain layer of the worldwide geological column would most likely be found, that would contain fossils of a certain type according to the ordering of fossils found in most parts of the geological column, along with certain characteristics of the rock normally associated with the kind of fossil they were seeking -- it was not a lucky find in a rock quarry (like Archaeopteryx), but one based on research and prediction, in turn based on previous evidence and the ordering of the geological column. Where and when, consistent with geology and the Flood.

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roxrkool
Member (Idle past 1067 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 15 of 42 (301739)
04-06-2006 6:42 PM
Reply to: Message 14 by Faith
04-06-2006 6:06 PM


Re: and you beat me to it.
You had it correct until the very last word. I must have missed the word "Flood" in the original text.
Additionally, geologists have a working model that helps predict where those rocks will be found in relation to other rocks, paleogeography. As far as I've seen, there is no Flood model that would allow us to do the same.

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