New Fossil Links Four-legged Land Animals To Ancient Fish

National Science Foundation ^ | 01 April 2004 | Staff

[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.

[PatrickHenry]

Why do Walruses have two feet?

I donno. But the rumor is that longshadow is moving to the tropics, where the competition is more to his liking.

[longshadow]

prodigious placemarker

[PatrickHenry]

Speak of the devil ...

[longshadow]

But the rumor is that longshadow is moving to the tropics, where the competition is more to his liking.

Better that than the "Everlasting Tropics," which is where the Creationist claim you are headed for a very long stay.....

[PatrickHenry]

Better that than the "Everlasting Tropics," which is where the Creationist claim you are headed for a very long stay.....

If God prefers the companionship of creos, then I have misjudged Him. In any event ... His will be done.

[Aracelis]

From Post 396 "No further correspondence necessary, goodbye."

Darn! And I was just going to ask him why God made introns. Never have gotten a sensible answer to that question from any Creationist...

[Aracelis]

the rumor is that longshadow is moving to the tropics, where the competition is more to his liking.

Perhaps he wishes to avoid an unfortunate "fracture".

[Aracelis]

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.

Not true at all...I have in fact spoken to RA previously about his spelling. That is, I did until discovering he is also an engineer (we know about those guys ;^) ), and the fact that he has rather large fingers. Conventional keyboards are not suitable for a man of his stature.

[Michael_Michaelangelo]

Hi there. Regarding introns, have you heard of the work done by Thomas Cech? His work in the 80's on enzymes and RNA laid the groundwork for additional studies that showed introns were far from 'junk'. The Tetrahymena ribozyme is an intron. Also, there are intron sequences that encode proteins that are required for the processing of DNA and RNA. Some introns have intrinsic catalytic activity. Others have been found to interfere with imprinting.

We may even find more uses for introns in the future. I believe information within the genome is 'layered' and we are yet to discover all the complexities within the design.

Link: RIBOZYMES: SCISSORS FROM AN OLD WORLD

[js1138]

Of course, in order to argue that molecular timescales are imprecise, you have to accept the precision of some other timescale, such as radioactive decay.

[RightWingNilla]

placemarkers all the way down placemarker

[Aracelis]

Fascinating link, and quite appropriate as I cram...er...study for an upcoming exam about this very subject on wednesday. My professor was trained at UC Boulder, and her emphasis is indeed RNA.

[hosepipe]

[ cover their ears with their hands and sing, "LA LA LA I CAN'T HEAR YOU". ]

Well, your preaching is not as loud as it is voluminous.
Everybody is preaching something more by what they do than by what they say..
So I don't fault you for that at all..

Theres far too many foundational items unsaid and maybe not possible here to be said to even engage on a subject like evolution. Except by hip shot advocates for religious and non religious claptrap, like evolution and many other secular religious and nonsecular religious fanciful notions and mental figments. And I don't have a cynical bone in my body.

Some folks are like secular Jehovah's Witnesses.. Pity. A word of caution:
Pointing at others and calling them idiots, remember you have 3 fingers pointed at yourself..(Eddie Murphy laugh)
Consider the medium your posting on.

[VadeRetro]

... he has rather large fingers. Conventional keyboards are not suitable for a man of his stature.

They say it's the thumbs that really tell the story.

[Dimensio]

I guess that you don't have any refutation to the information that Ichneumon provided? Why can't you just come out and say "I admit that I have absolutely no facts to back up my assertions"?

[RobRoy]

"They're trying to find themselves an audience. Their deductions need applause." - Genesis, The Lamb Lies Down on Broadway.

This is a classic example of the "jumping to conclusions" for which the church of Evolution is notorious.

I guess this bone just settles everything. Reminds me of a certain pigs tooth.

[js1138]

Everybody is preaching something more by what they do than by what they say..

The Bill clinton argument: everybody's doing it.

Sorry, but everybody isn't doing it. The poster you are attempting to clintonize is among the few who routinely offer carefully reasoned arguments.

To the best of my knowledge -- and I read nearly every word of these threads, no one has offered a word of rebuttal.

[RobRoy]

>>Darn! And I was just going to ask him why God made introns. Never have gotten a sensible answer to that question from any Creationist...<<

Whenever you want to know why God made something, it is best to ask him. Don't ask one of the pots why the potter put a handle on one. It's not their forte'.

[PatrickHenry]

This is a classic example of the "jumping to conclusions" for which the church of Evolution is notorious. I guess this bone just settles everything. Reminds me of a certain pigs tooth.

Actually, your post is a classic. I say that because of the following: (1) it's linked to post #1, thus you have reacted to the article only, and perhaps only to the title of the article, in a thread which is over 400 posts long; (2) you claim that the article is "jumping to conclusions," but you don't say what's wrong with it, nor do you provide your own conclusions, if you have any; (3) you mention "the church of Evolution," which -- although you probably don't understand why -- disqualifies you from serious participation in a debate on a science topic; (4) you vaguely mention "a certain pigs tooth," thus saying ... well, just what are you saying? Yes indeed, your post is a classic.

[RobRoy]

>>Actually, your post is a classic. I say that because of the following: (1) it's linked to post #1, thus you have reacted to the article only, and perhaps only to the title of the article, in a thread which is over 400 posts long; (2) you claim that the article is "jumping to conclusions," but you don't say what's wrong with it, nor do you provide your own conclusions, if you have any; (3) you mention "the church of Evolution," which -- although you probably don't understand why -- disqualifies you from serious participation in a debate on a science topic; (4) you vaguely mention "a certain pigs tooth," thus saying ... well, just what are you saying? Yes indeed, your post is a classic.<<

Me thinks thou doth protest too much. The article reads like so many of the Creationist articles – low on proof but high on conclusion. The masses are simply to accept the conclusions of their superiors and move along. No room for skeptics that question the quantity and quality of the evidence used to support the headline, much less the text of the story.

And yes, to MANY evolutionists (not all, of course) it IS a religion. That may disqualify me in your book but, IMO, your book has never really been particularly good reading anyway. So we both have different opinions.

Regarding “jumping to conclusions,” it speaks for itself. As I implied above, any rational reader could not come to the conclusions stated in the article based on the evidence provided there. There is no reason to point by point make that argument. The article is short, let the readers decide for themselves.

Regarding the pigs tooth, two words: Nebraska man.

True science bases hypotheses on evidence. Too many evolution “scientists” grab at any new find and shout, “see, I told you so” before analyzing all possible explanations. This exposes to strong a marriage to a hypothesis. Defending it so strongly requires the response, “Me thinks thou doth protest too much.”