Flatfish Fossils Fill In Evolutionary Missing Link

[Schrödinger's Cat]

Flatfish Fossils Fill In Evolutionary Missing Link

(emphasis mine)

ScienceDaily (July 10, 2008) — Hidden away in museums for more that 100 years, some recently rediscovered flatfish fossils have filled a puzzling gap in the story of evolution and answered a question that initially stumped even Charles Darwin.

Opponents of evolution have insisted that adult flatfishes, which have both eyes on one side of the head, could not have evolved gradually. A slightly asymmetrical skull offers no advantage. No such fish -- fossil or living -- had ever been discovered, until now.
All adult flatfishes--including the gastronomically familiar flounder, plaice, sole, turbot, and halibut--have asymmetrical skulls, with both eyes located on one side of the head. Because these fish lay on their sides at the ocean bottom, this arrangement enhances their vision, with both eyes constantly in play, peering up into the water.
This remarkable arrangement arises during the youth of every flatfish, where the symmetrical larva undergoes a metamorphosis to produce an asymmetrical juvenile. One eye 'migrates' up and over the top of the head before coming to rest in the adult position on the opposite side of the skull.
Opponents of evolution, however, insisted that this curious anatomy could not have evolved gradually through natural selection because there would be no apparent evolutionary advantage to a fish with a slightly asymmetrical skull but which retained eyes on opposite sides of the head. No fish--fossil or living--had ever been discovered with such an intermediate condition.
But in the 10 July 2008 issue of Nature, Matt Friedman, graduate student in the Committee on Evolutionary Biology at the University of Chicago and a member of the Department of Geology at the Field Museum, draws attention to several examples of such transitional forms that he uncovered in museum collections of underwater fossilized creatures from the Eocene epoch--about 50 million years ago.
"We owe this discovery, in part, to the European fondness for limestone," said Friedman. The fossils, which he found in museums in England, France, Italy, and Austria, came from limestone quarries in Northern Italy and underneath modern-day Paris.
Friedman examined multiple adult fossil remains of two primitive flatfishes, Amphistium and a new genus that he named Heteronectes.
"Amphistium has been known for quite some time," he said. "The first specimen was described more than 200 years ago, but its placement in the fish evolutionary tree has been uncertain ever since. Close examination of these fossils yield clues that they are indeed early flatfishes."
The most primitive flatfishes known, both Amphistium and Heteronectes have many characteristics that are no longer found in modern flatfish. But the one that caught Friedman's attention was the partial displacement of one eye, evident even in the first Amphistium fossil discovered over two centuries ago.
"Most remarkably," he said, "orbital migration, the movement of one eye from one side of the skull to the other during the larval stage, was present but incomplete in both of these primitive flatfishes." For both sets of fossils, the eye had begun the journey but had not crossed the midline from one side of the fish to the other.
"What we found was an intermediate stage between living flatfishes and the arrangement found in other fishes," he said. These two fossil fishes "indicate that the evolution of the profound cranial asymmetry of extant flatfishes was gradual in nature."
The Amphistium fossils were known and previously analyzed but not definitively linked to flatfish. Previous studies, relying on conventional techniques, did not detect the oddly shaped skull, but by performing CT scans on the fossils Friedman "unequivocally" demonstrated the cranial asymmetry.
Careful study of the Heteronectes chaneti fossil found that it represents a new genus. The genus name is derived from the Greek Heteros (different) and nectri (swimmer). The species, chaneti, honors Bruno Chanet, a pioneer in the study of fossil flatfish.
The two fossil sets "deliver the first clear picture of flatfish origins," said Friedman, "a hotly contested issue in debates on the mode and tempo of evolution."
Charles Darwin was baffled by what he referred to as the "remarkable peculiarity" of flatfish anatomy. "During early youth," he noted, the eyes "stand opposite to each other...Soon the eye proper to the lower side begins to glide slowly round the head to the upper side...The chief advantages thus gained seem to be protection from their enemies, and a facility for feeding on the ground."
Although the survival advantages of such asymmetry were clear, Darwin, when challenged, was unable to explain the mechanism of what appeared to be a rather sudden and radical change in morphology and suggested a Lamarckian adaptation in which the fish, through "muscular action," slowly pulled the down-side eye toward the upper side. The resulting distortion, he suggested, "would no doubt be increased through the principle of inheritance."
Darwin's explanation, which relied on the inheritance of acquired traits, preceded the discovery of genes, but geneticist Robert Goldschmidt, tackling the same flatfish issue in the 1930s, came up with a genetic explanation. He argued that such a sudden drastic change could be triggered by a single fortuitous mutation that triggered a deformity, which in some environments would prove beneficial--and then get passed on. He termed these sudden accidental evolutionary leaps "hopeful monsters," and made the mysterious origin of flatfishes the centerpiece of his argument.
Friedman's discovery eliminates the need for such optimistic accidents. It "refutes these claims of radical sudden change" he said, "and demonstrates that the assembly of the flatfish body plan occurred in a gradual, stepwise fashion."
The research was supported by grants from the Lerner-Grey Fund for Marine Research, the Hinds Fund, the Evolving Earth Fund, the National Science Foundation and the Environmental Protection Agency.

[7960]

will read more carefully later, but had to say this now..... as long as evolutionists are stuck in the rut of believing they need to refute claims by religious people they'll never win. they've "proven" this flatfish thing enough so the religious people will shut up about that, but they're just going to move on to the next one...and the next one...and the next one.

my opinion, scientists should start openly treating the religious people like idiots and basically ignoring them.

[Schrödinger's Cat]

Originally Posted by 7960

will read more carefully later, but had to say this now..... as long as evolutionists are stuck in the rut of believing they need to refute claims by religious people they'll never win. they've "proven" this flatfish thing enough so the religious people will shut up about that, but they're just going to move on to the next one...and the next one...and the next one.

I disagree. I don't think evolutionists are stuck in a rut. There's no need to refute claims of the religious, because the only ones that deny evolutionary facts are creationists. They aren't taken seriously in the scientific community or even outside some groups in the US. The religious will go on to the next thing, but that is what always happens. As the "mysteries" are explained by science, they have less things they need a god to explain. At one time God was invoked for just about every natural phenomenon, until completely natural explanations were discovered.

my opinion, scientists should start openly treating the religious people like idiots and basically ignoring them.

Have you read the books of leading evolutionary biologist, Richard Dawkins (he is by far not the only one)? Many scientists treat those people with scorn, but most do ignore them. However, when we say "religious people", I assume we are talking about Creationists. No one except creationist take creationists seriously. You can't take people seriously who will believe a conclusion and not require proof, but then trying to discredit scientific explanations with mountains of mutually supporting evidence. Outside of the US, it isn't even an issue, because it is only in the US that you have fundamentalists that are so hostile to real science. I say real science, because ID isn't science even though they claim it is. Even scientists who happen to be religious (e.g., Ken Miller) see right through that crap. There's a real ignorance in the US about what science actually is, the scientific method and the underlying means to get to the truth. Whenever science and religion clash, science always wins because it has evidence and rational argument, whereas religion has faith (belief because of a lack of evidence). It is no surprise that God is retreating from everyday life, because we don't need the supernatural to explain natural phenomena anymore. God is still only used to explain now what science has yet to come up with a solid answer; that is basically why these fundamentalists are hostile to science, because they see it as a threat to their faith. However, once again, this wouldn't even be an issue if a good size of the US electorate wasn't scientifically illiterate and scarily religious.

One of my favorite series on youtube is YouTube - Why do people laugh at creationists? (part 1).
Some other series that do a good job at flattening Creationism and ID:
YouTube - 1st Foundational Falsehood of Creationism
YouTube - 1 -- History of the Universe Made Easy (Part 1)

[7960]

Originally Posted by Schrödinger's Cat

However, when we say "religious people", I assume we are talking about Creationists. No one except creationist take creationists seriously.

I'm talking about people who want to put stickers on science books. I thought it was just insane creationists but then it happened 2 tows over from me and some people I otherwise thought were relatively normal signed on. Now, if I find out a person's religious opinions with having asked him I pretty much write him off as an idiot.

I'll watch those youtubes. Thanks

[Schrödinger's Cat]

Originally Posted by 7960

I'm talking about people who want to put stickers on science books. I thought it was just insane creationists but then it happened 2 tows over from me and some people I otherwise thought were relatively normal signed on. Now, if I find out a person's religious opinions with having asked him I pretty much write him off as an idiot.

I agree that it is insane. It is creationists and others, but both groups are religious fundamentalists. There have been many polls in the US about this. The results are extremely scary. The number of people in the US that believe the world is no more than 10K years old and was literally created as is, by God, is a serious detriment to our country. Any question why foreigners make fun of Americans for being ignorant?

Gallup and Pew polls:
Republicans, Democrats Differ on Creationism
Evolution, Creationism, Intelligent Design
Pew Research Center: Reading the Polls on Evolution and Creationism