Newly found species fills evolutionary gap between fish and land animals

EurekAlert (AAAS) ^ | 05 April 2006 | Staff

[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.

[mlc9852]

I observed flowers blooming. Material fact?

[King Prout]

"the FIRST peer reviewed journal article concerning plate tectonics" could have appeared yesterday, and I would be perfectly comfortable.

moreover, "the FIRST peer reviewed journal article concerning plate tectonics" could have appeared yesterday, and your doubled-absolute statement would *still* be false.

just admit it - you made a gross overstatement.
just pledge to attempt to avoid doing it again.

then I might interested in seeing your posts.
until then, well... trading barbs with artful dodgers doesn't appeal to me.

so, again: good day.

[Zavien Doombringer]

you are taking the passage out of context... NIV Isaiah 59:10-16

10 We grope for the wall like the blind; we grope like those who have no eyes; we stumble at noon as in the twilight, among those in full vigor we are like dead men. 11 We all growl like bears; we moan and moan like doves; we hope for justice, but there is none; for salvation, but it is far from us. 12 For our transgressions are multiplied before you, and our sins testify against us; for our transgressions are with us, and we know our iniquities: 13 transgressing, and denying the Lord, and turning back from following our God, speaking oppression and revolt, conceiving and uttering from the heart lying words. 14 Justice is turned back, and righteousness stands afar off; for truth has stumbled in the public squares, and uprightness cannot enter. 15 Truth is lacking, and he who departs from evil makes himself a prey

But this scripture is fitting for this discussion, to take evolution for what it is, it is like stumbling...

[jec41]

I observed flowers blooming. Material fact?

Yep

[metmom]

There's a lot evolution doesn't address.

[jennyp]

I need more responses to this important survey regarding transitional fossils:

Which of the following are "just an old ape" and which are "just an old human"? Try it, it's fun!

Fossil hominid skulls. Some of the figures have been modified for ease of comparison
(only left-right mirroring or removal of a jawbone). [CLICK HERE] for larger photo.
(Images © 2000 Smithsonian Institution.)

• (A) Pan troglodytes, chimpanzee, modern
  
• (B) Australopithecus africanus, STS 5, 2.6 My
  
• (C) Australopithecus africanus, STS 71, 2.5 My
  
• (D) Homo habilis, KNM-ER 1813, 1.9 My
  
• (E) Homo habilis, OH24, 1.8 My
  
• (F) Homo rudolfensis, KNM-ER 1470, 1.8 My
  
• (G) Homo erectus, Dmanisi cranium D2700, 1.75 My
  
• (H) Homo ergaster (early H. erectus), KNM-ER 3733, 1.75 My
  
• (I) Homo heidelbergensis, "Rhodesia man", 300,000 - 125,000 y
  
• (J) Homo sapiens neanderthalensis, La Ferrassie 1, 70,000 y
  
• (K) Homo sapiens neanderthalensis, La Chappelle-aux-Saints, 60,000 y
  
• (L) Homo sapiens neanderthalensis, Le Moustier, 45,000 y
  
• (M) Homo sapiens sapiens, Cro-Magnon I, 30,000 y
  
• (N) Homo sapiens sapiens, modern

We know that A) is a modern chimpanzee and N) is a modern human. Everyone agrees that M) was a modern human as well. Your challenge is to fill in these blanks:

Fossil	Just an ape	Ape-like transitional	Human-like transitional	Just a human	Not related at all to apes or humans
B	[_]	[_]	[_]	[_]	[_]
C	[_]	[_]	[_]	[_]	[_]
D	[_]	[_]	[_]	[_]	[_]
E	[_]	[_]	[_]	[_]	[_]
F	[_]	[_]	[_]	[_]	[_]
G	[_]	[_]	[_]	[_]	[_]
H	[_]	[_]	[_]	[_]	[_]
I	[_]	[_]	[_]	[_]	[_]
J	[_]	[_]	[_]	[_]	[_]
K	[_]	[_]	[_]	[_]	[_]
L	[_]	[_]	[_]	[_]	[_]

The Responses So Far:

Person	A Pan troglodytes (modern chimp)	B, C Australopithecus africanus	D Homo habilis	E Homo habilis	F Homo rudolfensis	G Homo erectus	H Homo ergaster	I Homo heidelbergensis	J, K Homo sapiens neanderthalensis	L, M Homo sapiens sapiens (Cro-Magnon, modern human)
Mainstream scientists	ape	ape-like trans	ape-like trans	ape-like, human-like trans	ape-like, human-like trans	human-like trans	human-like trans	human-like trans	human-like trans, human	human
editor-surveyor	ape	ape	ape	ape	ape	ape	ape	ape	human	human
Michael_Michaelangelo	ape	ape	ape	ape	ape	ape	ape	ape	human	human
MississippiMan	ape							ape		human

[metmom]

(Ya left off...

"And that's the absolute truth!"

But don't you know *there are no absolutes*. Except that statement, which is expected to be taken as an absolute. But if there are no absolutes, that would include that statement. So then, that statement is false; there are indeed absolutes.

[balrog666]

You don't know what an "argument" is, do you? You think it is people diagreeing, don't you?

Shades of Monty Python!

[freedumb2003]

Shades of Monty Python!

I could be arguing on my spare time!;)

[muawiyah]

Virgin births are a dime a dozen these days. So, what about it?

[gomaaa]

Does order come of chaos by itself? Prove it.

It happens all the time

http://www.its.caltech.edu/~atomic/snowcrystals/

Ordered states are often a more energetically favorable configuration than unordered states. This is how crystalization occurs.

[muawiyah]

Certainly there's room for determining what the mind might be.

[dread78645]

Q: Don't give me that, you snotty-faced heap of parrot droppings!
M: What?
Q: Shut your festering gob, you tit! Your type really makes me puke, you vacuous, coffee-nosed, maloderous, pervert!!!
M: Look, I CAME HERE FOR AN ARGUMENT, I'm not going to just stand...!!
Q: OH, oh I'm sorry, but this is abuse.
M: Oh, I see, well, that explains it.
Q: Ah yes, you want room 12A, Just along the corridor.
M: Oh, Thank you very much. Sorry.
Q: Not at all.
M: Thank You.
(Under his breath) Stupid git!!

[muawiyah]

Scientific American recently ran an editorial on the matter ~ there are many sources for such claims.

For some reason no one is suggesting that these guys are nutcases ~ which they are ~

[jec41]

Certainly there's room for determining what the mind might be.

That is not a argument I would consider.

[muawiyah]

They do?

Amazing.

I think you are confusing their belief or understanding of additional dimensionality with your very limited "objective reality" that's grounded in a mere three dimensions.

[CarolinaGuitarman]

"But don't you know *there are no absolutes*."

Do you believe that there is such a thing as objective reality?; that the existence of the world is not dependent on who the observer is?


If so, you need to talk to muawiyah. He/she says that objective reality doesn't exist (not just that we can't know it with certainty). Also, he/she claims that Christians don't believe that the Bible is objectively true. He/she also claimed that the universe could be a construct of his mind.

He/she is not one of us. What say you?

[muawiyah]

Without an understanding of the concepts "dark matter" and "dark energy" you can't begin to get a grasp of the small fraction of the Universe that's measurable and observable.

So much for materialism ~ it's only a trivial part of knowledge.

[muawiyah]

Hardly ~ in fact, I read it in the library of the geology building at Indiana University in my undergraduate days.

Up until the publication of that particular study, it was mere conjecture. After the publication, it became accepted doctrine.

(NOTE: Nothing like being there at the foundations ~ remember, the past is not like the present ~ it really is stranger than you can imagine, unless you remember it.)

[CarolinaGuitarman]

"They do?

Amazing."

Yes, your claim is amazing.

"I think you are confusing their belief or understanding of additional dimensionality with your very limited "objective reality" that's grounded in a mere three dimensions."

No, I am speaking of the 4 dimensions that we can have objective knowledge about. Christians most certainly DO believe that there is objective truth in the Bible.

Postmodernist relativism will be the death of conservatism .