Fossil Called Missing Link From Sea to Land Animal

[davemania]

Scientists have discovered fossils of a 375-million-year-old fish, a large scaly creature not seen before, that they say is a long-sought missing link in the evolution of some fishes from water to a life walking on four limbs on land.

In two reports today in the journal Nature, a team of scientists led by Neil H. Shubin of the University of Chicago say they have uncovered several well-preserved skeletons of the fossil fish in sediments of former streambeds in the Canadian Arctic, 600 miles from the North Pole.

The skeletons have the fins, scales and other attributes of a giant fish, four to nine feet long. But on closer examination, the scientists found telling anatomical traits of a transitional creature, a fish that is still a fish but has changes that anticipate the emergence of land animals ? and is thus a predecessor of amphibians, reptiles and dinosaurs, mammals and eventually humans.

In the fishes' forward fins, the scientists found evidence of limbs in the making. There are the beginnings of digits, proto-wrists, elbows and shoulders. The fish also had a flat skull resembling a crocodile's, a neck, ribs and other parts that were similar to four-legged land animals known as tetrapods.

Other scientists said that in addition to confirming elements of a major transition in evolution, the fossils were a powerful rebuttal to religious creationists, who have long argued that the absence of such transitional creatures are a serious weakness in Darwin's theory.

The discovery team called the fossils the most compelling examples yet of an animal that was at the cusp of the fish-tetrapod transition. The fish has been named Tiktaalik roseae, at the suggestion of elders of Canada's Nunavut Territory. Tiktaalik (pronounced tic-TAH-lick) means "large shallow water fish."

"The origin of limbs," Dr. Shubin's team wrote, "probably involved the elaboration and proliferation of features already present in the fins of fish such as Tiktaalik."

In an interview, Dr. Shubin, an evolutionary biologist, let himself go. "It's a really amazing, remarkable intermediate fossil," he said. "It's like, holy cow."

Two other paleontologists, commenting on the find in a separate article in the journal, said that a few other transitional fish had been previously discovered from approximately the same Late Devonian time period, 385 million to 359 million years ago. But Tiktaalik is so clearly an intermediate "link between fishes and land vertebrates," they said, that it "might in time become as much an evolutionary icon as the proto-bird Archaeopteryx," which bridged the gap between reptiles (probably dinosaurs) and today's birds.

The writers, Erik Ahlberg of Uppsala University in Sweden and Jennifer A. Clack of the University of Cambridge in England, are often viewed as rivals to Dr. Shubin's team in the search for intermediate species in the evolution from fish to the first animals to colonize land.

H. Richard Lane, director of paleobiology at the National Science Foundation, said in a statement, "These exciting discoveries are providing fossil 'Rosetta Stones' for a deeper understanding of this evolutionary milestone ? fish to land-roaming tetrapods."

The science foundation and the National Geographic Society were among the financial supporters of the research. Besides Dr. Shubin, the principal discoverers were Edward B. Daeschler of the Academy of Natural Sciences in Philadelphia and Farish A. Jenkins Jr., a Harvard evolutionary biologist. Casts of the fossils will be on view at the Science Museum of London.

Michael J. Novacek, a paleontologist at the American Museum of Natural History in Manhattan, who was not involved in the research, said: "Based on what we already know, we have a very strong reason to think tetrapods evolved from lineages of fishes. This may be a critical phase in that transition that we haven't had before. A good fossil cuts through a lot of scientific argument."

Dr. Shubin's team played down the fossil's significance in the raging debate over Darwinian theory, which is opposed mainly by some conservative Christians in this country, but other scientists were not so reticent. They said this should undercut the argument that there is no evidence in the fossil record of one kind of creature becoming another kind.

One creationist site on the Web (emporium.turnpike.net/C/cs /evid1.htm) declares that "there are no transitional forms," adding: "For example, not a single fossil with part fins, part feet has been found. And this is true between every major plant and animal kind."

Dr. Novacek responded: "We've got Archaeopteryx, an early whale that lived on land, and now this animal showing the transition from fish to tetrapod. What more do we need from the fossil record to show that the creationists are flatly wrong?"

Duane T. Gish, a retired official of the Institute for Creation Research in San Diego, said, "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."

Dr. Shubin and Dr. Daeschler began their search on Ellesmere Island in 1999. They were attracted by a map in a geology textbook showing an abundance of Devonian rocks exposed and relatively easy to explore. At that time, the land had a warm climate: it was part of a supercontinent straddling the Equator.

It was not until July 2004, Dr. Shubin said, that "we hit the jackpot." They found several of the fishes in a quarry, their skeletons largely intact and in three dimensions. The large skull had the sharp teeth of a predator. It was attached to a neck, which allowed the fish the unfishlike ability to swivel its head.

If the animal spent any time out of water, said Dr. Jenkins, of Harvard, it needed a true neck that allowed the head to move independently on the body.

Embedded in the pectoral fins were bones that compare to the upper arm, forearm and primitive parts of the hand of land-living animals. The joints of the fins appeared to be capable of functioning for movement on land, a case of a fish improvising with its evolved anatomy. In all likelihood, the scientists said, Tiktaalik flexed its proto-limbs mainly on the floor of streams and might have pulled itself up on the shore for brief stretches.

In their report, the scientists concluded that Tiktaalik was an intermediate between the fishes Eusthenopteron and Panderichthys, which lived 385 million years ago, and early tetrapods. The known early tetrapods are Acanthostega and Ichthyostega, about 365 million years ago.

Tiktaalik, Dr. Shubin said, is "both fish and tetrapod, which we sometimes call a fishapod."

http://www.nytimes.com/2006/04/06/science/...mzZ9HvL/XntErxg

[pto]

Oh evolution, i wonder how sexy of a species we will become.

[devn00b]

Scientists have made one of the most important fossil finds in history: a missing link between fish and land animals, showing how creatures first walked out of the water and on to dry land more than 375m years ago.

Palaeontologists have said that the find, a crocodile-like animal called the Tiktaalik roseae and described today in the journal Nature, could become an icon of evolution in action - like Archaeopteryx, the famous fossil that bridged the gap between reptiles and birds.

As such, it will be a blow to proponents of intelligent design, who claim that the many gaps in the fossil record show evidence of some higher power.

Richard Dawkins, the evolutionary biologist, said: "Our emergence on to the land is one of the more significant rites of passage in our evolutionary history, and Tiktaalik is an important link in the story."

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 scientists who discovered it say the animal was a predator with sharp teeth, a crocodile-like head, and a body that grew up to 2.75 metres (9ft) long.

"It's very important for a number of reasons, one of which is simply the fact that it's so well-preserved and complete," said Jennifer Clack, a paleontologist at Cambridge University and author of an accompanying article in Nature.

Scientists have previously been able to trace the transition of fish into limbed animals only crudely over the millions of years they anticipate the process took place. They suspected that an animal which bridged the gap between fish and land-based tetrapods must have existed - but, until now, there had been scant evidence of one.

"Tiktaalik blurs the boundary between fish and land-living animal both in terms of its anatomy and its way of life," said Neil Shubin, a biologist at the University of Chicago, and a leader of the expedition which found Tiktaalik.

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.

Farish Jenkins, an evolutionary biologist at Harvard University said: "This represents a critical early phase in the evolution of all limbed animals, including humans - albeit a very ancient step." Tiktaalik also gives biologists a new understanding of how fins turned into limbs. Its fin contains 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," 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."

H Richard Lane, director of sedimentary geology and palaeobiology at the US National Science Foundation, said: "These exciting discoveries are providing fossil Rosetta stones for a deeper understanding of this evolutionary milestone - fish to land-roaming tetrapods."

A cast of the fossil goes on display at the Science Museum in South Kensington central London today.

Source: http://www.guardian.co.uk/science/story/0,,1747926,00.html

[xpgeek]

I always said Intelligent Design was a load of crap, so this is fantastic news.

[Axel]

Awesome. What is this intelligent design crap anyway? Evolution is a fore-gone conclusion.

Edited April 6, 2006 by Axel

[sanghoku]

i wonder what t he next milestone in evolution will be... mindlink? breathing under water (with the melting ice and increasing water levels)? huge brains (with the increasing amount of knowledge we have to learn to cope with day in day out)?

[xpgeek]

Intelligent Design is a theory, I refuse to call it a scientific theory, that says humans are sooo complex, there just must have been some 'supernatural force' that played a part in our creation. They're trying to force it into schools and science classes. If you ask me, its a way to talk about god without actually mentioning him, a backdoor way to get religion back into the public schools.

And I've read in a couple hundred years from now, humans brains will actually be smaller not larger. As they become more efficient and more complex they don't need to be as large.

[Malisk]

And I've read in a couple hundred years from now, humans brains will actually be smaller not larger. As they become more efficient and more complex they don't need to be as large.

Yeah; the human brain would've been larger already if evolution wouldn't have only the restricted space of the cranium to work with, that has to be restricted or a woman wouldn't be able to give birth well. It's bad enough as it is already about these things. :) So, to keep increasing the area size of the brain, it's twisted a lot. Less intelligent species than the human with similar sizes have less twisting going on.

I also agree with what you say about intelligent design; it's a theory, but for it to be scientific, they need to empirically prove there is a God as this theory relies on that aspect, and science is all about empirical evidence. If they can't, they need to accept others calling the theory flawed or having problems, if it's supposed to be a scientific one. Just like many scientists call the dark matter theory problematic today, because we have little empirical evidence supporting it. This is how science have always worked, since the days of Archimedes, and before. But I really think ID followers aren't so interested in doing that; all most followers of that one wish isn't to act like scientists, but spread a religion or belief. That it's a belief, I can agree with, because beliefs don't have the strict requirements of empirical proof as scientific theories have.

[Aaron Veteran]

Thread moved.

[dreamz Veteran]

threads merged

this is an awesome finding.

[The_Decryptor Veteran]

This is a cool find. :yes:

Intelligent Design is a theory, I refuse to call it a scientific theory

...

While it's not a scientific theory, i wouldn't even call it theory, it's creationism wrapped up in the guise of science.

[zeroday]

there is no way that random mutations can bring about human beings. we are too complex for that.

http://www.harunyahya.com/20questions02.php

[davemania]

there is no way that random mutations can bring about human beings. we are too complex for that.

http://www.harunyahya.com/20questions02.php

Claim CA100:

It is inconceivable that (fill in the blank) could have originated naturally. Therefore, it must have been created.

This argument, also known as the argument from ignorance or "god of the gaps," is implicit in a very many different creationist arguments. In particular, it is behind all arguments against abiogenesis and any and all claims of intelligent design.

Response:

1. Really, the claim is "I can't conceive that (fill in the blank)." Others might be able to find a natural explanation; in many cases, they already have. Nobody knows everything, so it is unreasonable to conclude that something is impossible just because you do not know it. Even a noted antievolutionist acknowledges this point: "The peril of negative arguments is that they may rest on our lack of knowledge, rather than on positive results" (Behe 2003).

2. The argument from incredulity creates a god of the gaps. Gods were responsible for lightning until we determined natural causes for lightning, for infectious diseases until we found bacteria and viruses, for mental illness until we found biochemical causes for them. God is confined only to those parts of the universe we do not know about, and that keeps shrinking.

http://www.talkorigins.org/indexcc/CA/CA100.html

Randomness is one of the most misunderstood term in evolution.

It is grindingly, creakingly, obvious that, if Darwinism were really a theory of chance, it couldn't work. [Dawkins 1996: 67]

Darwinism is widely misunderstood as a theory of pure chance. Mustn't it have done something to provoke this canard? Well, yes, there is something behind the misunderstood rumour, a feeble basis to the distortion. one stage in the Darwinian process is indeed a chance process -- mutation. Mutation is the process by which fresh genetic variation is offered up for selection and it is usually described as random. But Darwinians make the fuss they do about the 'randomness' of mutation only in order to contrast it to the non-randomness of selection. It is not necessary that mutation should be random for natural selection to work. Selection can still do its work whether mutation is directed or not. Emphasizing that mutation can be random is our way of calling attention to the crucial fact that, by contrast, selection is sublimely and quintessentially non-random. It is ironic that this emphasis on the contrast between mutation and the non-randomness of selection has led people to think that the whole theory is a theory of chance.

Even mutations are, as a matter of fact, non-random in various senses, although these senses aren't relevant to our discussion because they don't contribute constructively to the improbable perfection of organisms. For example, mutations have well-understood physical causes, and to this extent they are non-random. ... the great majority of mutations, however caused, are random with respect to quality, and that means they are usually bad because there are more ways of getting worse than of getting better. [Dawkins 1996:70-71]

[John Veteran]

there is no way that random mutations can bring about human beings. we are too complex for that.

http://www.harunyahya.com/20questions02.php

The first paragraph alone makes it obvious the auther is not open to the realm of possibility. Consider the "monkeys on a keyboard" situation. Leave 10,000 monkeys to type on a keyboard (not knowing what they keys mean or having any consious awareness of what they're doing) and eventually you will come up with a working software program. Now, the ratio of working software code to random character strings is nearly 1 to infinity, but it does happen.

THE theory of evolution maintains that life on Earth came about as the result of chance and emerged by itself from natural conditions. This theory is not a scientific law or a proven fact. Underneath its scientific fa?ade it is a materialist worldview that Darwinists are trying to impose on society. The bases of this theory, which has been disproved by science in every field, are suggestions and propaganda methods consisting of deceptions, falsehood, contradiction, cheating, and sleight of hand.

Stating the theory of evolution is propaganda and is being imposed on society by Darwinists sounds like fear to me. Fear that the theory exists to prove the non-existence of God, fear that the theory does not account for the possibility (or likelihood) of a God, fear that there is nothing more to the universe than what seems apparent. However I believe the theory of evolution and God coexist, and they do so without our full understanding of either one of them.

I take the theory of evolution to be just this: cells can (and do) evolve over time into more complex (and arguably, intelligent) versions of themselves. On a biological level, a species will continue to grow and mature into a "better" species more suited to its environment. Sometimes this meansevolving> into a completely different (though related) species - sometimes it does not.

From my perspective, the theory of evolution does not account for the origin of thefirst> biologically "living" cell. If we leave the origin of this cell to the theory of evolution, it must haveevolved> from something (ie. another cell). Obviously this isn't the case. There are many possibilities for the result of this cell, most of which I believe a God would be the cause of.

I believe God created (among other things) the first living cell. Then he left it alone, to multiply, mutate, and evolve on its own. Over billions of years, cells diversified based on their surroundings and grouped together. This accounts for tissues, organs, and organisms themselves. This whole time, the cell itself hasevolved> on a cellular level. I believe cells continue to evolve in every modern day species, but those species themselves evolve on a higher level as well (from one genus to another, for example).

Edited May 1, 2006 by John

[MacOSXMan]

^_^ (Y) John made a great point, I agree with everything he said.

[The_Decryptor Veteran]

That site is, well, crap.

Saying that evolution has no evidence, and is just some form of conspiracy by scientists, shows that the author of the page has no idea about Evolution.

Evolution is a scientific theory, because it has evidence to back it up, and can be tested, the tests are repeatable, people get confused over the meaning of the word theory, and use that to say that it has no evidence.

And even today, we see evolution is happening, species isolated from other members of it's species, in a different environment, have evolved to fit into their surroundings.

[dreamz Veteran]

The first paragraph alone makes it obvious the auther is not open to the realm of possibility. Consider the "monkeys on a keyboard" situation. Leave 10,000 monkeys to type on a keyboard (not knowing what they keys mean or having any consious awareness of what they're doing) and eventually you will come up with a working software program. Now, the ratio of working software code to random character strings is nearly 1 to infinity, but it does happen.

not to mention the fact that if useful bits are saved, e.g., the correct letters in a sentence in the correct position, the time required is reduced drastically. this has been seen in several computational and simulation experiments.

Fear that the theory exists to prove the non-existence of God, fear that the theory does not account for the possibility (or likelihood) of a God, fear that there is nothing more to the universe than what seems apparent.

i would agree with this part. some people don't like thinking that they aren't perfect, aren't divinely created beings. i tend to see it the other way. that nature could have yielded us is an amazing feat indeed. there is nothing greater.

i would also argue that there is a difference between fact and what people find offensive. there is no necessary correspondence.

I believe God created (among other things) the first living cell. Then he left it alone, to multiply, mutate, and evolve on its own.

i disagree with this point. positing a first god is just as arbitrary and as explanatory as positing a spontaneously generated universe.

Saying that evolution has no evidence, and is just some form of conspiracy by scientists, shows that the author of the page has no idea about Evolution.

unfortunately, there are many people like that, people who have never read real books about it, or scientific literature.

Evolution is a scientific theory, because it has evidence to back it up, and can be tested, the tests are repeatable, people get confused over the meaning of the word theory, and use that to say that it has no evidence.

And even today, we see evolution is happening, species isolated from other members of it's species, in a different environment, have evolved to fit into their surroundings.

in this case, i would differentiate between observations and sentences about those observations. people tend to view evolution as a single entity when it actually comprises both. i would argue that there are competing theories (e.g., punctuated equilibrium, natural selection, etc.) that develop and assess the mechanisms using the observations as a starting point. it's not like people came up with evolution because they wanted to spite religious folk or because it's fanciful. if it is believed scientifically, it is because it is supported by evidence and it simplifies the whole network of theories and sentences.