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New Fossil Links Four-legged Land Animals To Ancient Fish
National Science Foundation ^ | 01 April 2004 | Staff

Posted on 04/02/2004 4:25:18 PM PST by PatrickHenry

Arlington, Va.—How land-living animals evolved from fish has long been a scientific puzzle. A key missing piece has been knowledge of how the fins of fish transformed into the arms and legs of our ancestors. In this week's issue of the journal Science, paleontologists Neil Shubin and Michael Coates from the University of Chicago and Ted Daeschler from the Academy of Natural Sciences in Philadelphia, describe a remarkable fossil that bridges the gap between fish and amphibian and provides a glimpse of the structure and function changes from fin to limb.

The fossil, a 365-million-year-old arm bone, or humerus, shares features with primitive fish fins but also has characteristics of a true limb bone. Discovered near a highway roadside in north-central Penn., the bone is the earliest of its kind from any limbed animal.

"It has long been understood that the first four-legged creatures on land arose from the lobed-finned fishes in the Devonian Period," said Rich Lane, director of the National Science Foundation's (NSF) geology and paleontology program. "Through this work, we've learned that fish developed the ability to prop their bodies through modification of their fins, leading to the emergence of tetrapod limbs."

NSF, the independent federal agency that supports fundamental research and education across all fields of science and engineering, funded the research.

The bone's structure reveals an animal that had powerful forelimbs, with extensive areas for the attachment of muscles at the shoulder. "The size and extent of these muscles means that the humerus played a significant role in the support and movement of the animal," reported Shubin. "These muscles would have been important in propping the body up and pushing it off of the ground."

Interestingly, modern-day fish have smaller versions of the muscles. According to Coates, "When this humerus is compared to those of closely-related fish, it becomes clear that the ability to prop the body is more ancient than we previously thought. This means that many of the features we thought evolved to allow for life on land originally evolved in fish living in aquatic ecosystems."

The layered rock along the Clinton County, Penn., roadside were deposited by ancient stream systems that flowed during the Devonian Period, about 365 million years ago. Enclosed in the rocks is fossil evidence of an ecosystem teeming with plant and animal life. "We found a number of interesting fossils at the site," reported Daeschler, who uncovered the fossil in 1993. "But the significance of this specimen went unnoticed for several years because only a small portion of the bone was exposed and most of it lay encased in a brick-sized piece of red sandstone."

Not until three years ago, when Fred Mullison, the fossil preparator at the Academy of Natural Sciences, excavated the bone from the rock, did the importance of the new specimen become evident.

The work was also funded by a grant from the National Geographic Society.


TOPICS: Culture/Society; Philosophy
KEYWORDS: biology; creationism; crevolist; darwin; evolution; godsgravesglyphs; michaelcoates; neilshubin; paleontology; teddaeschler
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To: Piltdown_Woman
Irrelevant, as we Piltdowns have all evolved.

Whoohoo! Evolved is right. :-)

381 posted on 04/05/2004 6:16:18 AM PDT by RadioAstronomer
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To: daddyOwe
...but I only have two legs...

You have four, just like all the other tetrapods. Your forelegs are simply modified for purposes other than locomotion, now.

382 posted on 04/05/2004 6:56:18 AM PDT by Junior (Remember, you are unique, just like everyone else.)
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To: js1138; Piltdown_Woman
Further comparing notes, vpintheak is in the lead for "fastest unraveling."
383 posted on 04/05/2004 7:12:52 AM PDT by VadeRetro
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To: Piltdown_Woman; RadioAstronomer; longshadow; VadeRetro; balrog666
Late-breaking science news that may interest you, from Nature:
Size does matter: Prominent penis gives cold-dwelling mammals an edge.

My customary good taste prevents me from posting it as a stand-alone thread.

384 posted on 04/05/2004 7:48:40 AM PDT by PatrickHenry (Hic amor, haec patria est.)
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To: PatrickHenry
I'm glad Senator Schumer (D-NY) is doing something for the cold-dwelling mammals.
385 posted on 04/05/2004 7:58:40 AM PDT by VadeRetro
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To: RadioAstronomer
You are right, teach both evolution and creationism. Let's be fair here. Either both or neither. You can't have it all your way.
386 posted on 04/05/2004 7:59:13 AM PDT by fish hawk
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To: fish hawk
Actually we can, because one is science and the other is religion.
387 posted on 04/05/2004 8:04:34 AM PDT by js1138 (In a minute there is time, for decisions and revisions which a minute will reverse. J Forbes Kerry)
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To: js1138
No, they both are religion. Evolution is the god to many on this thread.
388 posted on 04/05/2004 8:07:26 AM PDT by fish hawk
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To: fish hawk
You are right, teach both evolution and creationism. Let's be fair here. Either both or neither. You can't have it all your way.

Fairness is what matters. What is truth, anyway, right?

Holy Warrior Syndrome.

You may say that something is wrong, but who is to say you're right? You may say that the evidence excludes a thing, but who is to say what is evidence? Is your reality any more valid than anyone else's?
Liberals and creationists! You got it bad.
389 posted on 04/05/2004 8:10:20 AM PDT by VadeRetro
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To: fish hawk
And if you were king of the world you pathetic bleatings would be tthe law, and you could imprison anyone who disagreed. But, alas for you, you are not, and no one cares about your attempts to redefine reality.
390 posted on 04/05/2004 8:11:30 AM PDT by js1138 (In a minute there is time, for decisions and revisions which a minute will reverse. J Forbes Kerry)
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To: js1138
Then why do you keep writing me? You just like to argue?
391 posted on 04/05/2004 8:22:52 AM PDT by fish hawk
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To: VadeRetro
You are right about Creationist, but Liberal? I guess you have to label everyone. The best Conservatives I know are Christians. Without us you would be a lost minority.
392 posted on 04/05/2004 8:26:11 AM PDT by fish hawk
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To: fish hawk
My impression is that most Christians are not creationists. At any rate, I tend to notice commonalities between how liberals and creationists argue. From the other side, it tends to look like this:

A recent post of yours reminded me of the last point in particular.
393 posted on 04/05/2004 8:32:22 AM PDT by VadeRetro
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To: fish hawk
I guess you have to label everyone.

Exactly how John Kerry answers when asked "Are you a liberal?"

394 posted on 04/05/2004 8:33:21 AM PDT by VadeRetro
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To: VadeRetro
Your "impression" is that evolution is fact. You are an Impressionist. This is really fun, but I have to go to work now. Oh, I forgot to SHOUT this. LOL
395 posted on 04/05/2004 8:46:19 AM PDT by fish hawk
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To: Piltdown_Woman
As per my previous post. It is obvious that you think myself and other Christians are morons because we don't have so much faith in human scientific knowledge. Yes I have run up against nothing but people patronizing me whenever I do have these types of discussions. I really don't care if you aren't as nice. I will continue to pray for all of us. Did I misspell any words this time? I sure hope not, I would hate to make a mistake once in a while. No further correspondence necessary, goodbye.
396 posted on 04/05/2004 8:47:05 AM PDT by vpintheak (Our Liberties we prize, and our rights we will maintain!)
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To: vpintheak
Did I misspell any words this time? I sure hope not, I would hate to make a mistake once in a while.

The funny thing is, RA made a spelling mistake in the post prior to yours and she must not have noticed. Course, evo's would never criticize a scientist.

397 posted on 04/05/2004 8:58:05 AM PDT by Michael_Michaelangelo
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To: PatrickHenry
At last, we've explained what 'I am the walrus' means!
398 posted on 04/05/2004 8:58:42 AM PDT by Right Wing Professor
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Course, evo's would never criticize a scientist.

Scientists criticizing scientists is a good thing, however, for that is how we advance our knowledge. Here is a recent example.

Molecular timescales of evolution are imprecise

399 posted on 04/05/2004 9:03:31 AM PDT by Michael_Michaelangelo
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To: PatrickHenry
Walruses (Odobenus), however, which live in the frozen Arctic, weigh less, at up to 1,700 kilograms, but have a baculum that can reach up to 60 centimetres in length - one of the largest members of any mammal in both absolute and relative terms.

Brings up the old joke -- Why do Walruses have two feet?

400 posted on 04/05/2004 9:10:11 AM PDT by Junior (Remember, you are unique, just like everyone else.)
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