Posted on 12/10/2006 5:29:49 PM PST by shrinkermd
Oxygen may be the clue to first appearance of large animals, says Queen’s prof
The sudden appearance of large animal fossils more than 500 million years ago – a problem that perplexed even Charles Darwin and is commonly known as “Darwin’s Dilemma” – may be due to a huge increase of oxygen in the world’s oceans, says Queen’s paleontologist Guy Narbonne, an expert in the early evolution of animals and their ecosystems.
In 2002, Dr. Narbonne and his research team found the world’s oldest complex life forms between layers of sandstone on the southeastern coast of Newfoundland. This pushed back the age of Earth’s earliest known complex life to more than 575 million years ago, soon after the melting of the massive “snowball” glaciers. New findings reported today shed light on why, after three billion years of mostly single-celled evolution, these large animals suddenly appeared in the fossil record.
In a paper published on-line in Science Express, Dr. Narbonne’s team argues that a huge increase in oxygen following the Gaskiers Glaciation 580 million years ago corresponds with the first appearance of large animal fossils on the Avalon Peninsula in Newfoundland.
Now for the first time, geochemical studies have determined the oxygen levels in the world’s oceans at the time these sediments accumulated in Avalon. “Our studies show that the oldest sediments on the Avalon Peninsula, which completely lack animal fossils, were deposited during a time when there was little or no free oxygen in the world’s oceans,” says Dr. Narbonne. “Immediately after this ice age there is evidence for a huge increase in atmospheric oxygento at least 15 per cent of modern levels, and these sediments also contain evidence of the oldest large animal fossils.”
Also on the research team are Don Canfield (University of Southern Denmark) and Simon Poulton (Newcastle University, U.K.). Geochemical studies by Drs. Canfield and Poulton included measurements of iron speciation and sulphur isotopes to determine the oxygen levels in the world’s oceans at the time these sediments accumulated in Avalon.
The close connection between the first appearance of oxygenated conditions in the world’s oceans and the first appearance of large animal fossils confirms the importance of oxygen as a trigger for the early evolution of animals, the researchers say. They hypothesize that melting glaciers increased the amount of nutrients in the ocean and led to a proliferation of single-celled organisms that liberated oxygen through photosynthesis. This began an evolutionary radiation that led to complex communities of filter-feeding animals, then mobile bilateral animals, and ultimately to the Cambrian “explosion” of skeletal animals 542 million years ago.
For a fuller study of fluctuating oxygen levels through geologic time, and it's possible effects on the development of life, try Peter D. Ward's OUT OF THIN AIR (Joseph Henry Press, 2006).
My understanding is that "sudden" to the above mentioned fellows means appearing in the strata with insufficent precursors in the lower strata to explain them.
But what do I know, I'm a blue collar guy.
Sadly the hoi polloi have not been blessed with the superior intellect of the technocrats.
You want to discuss science with folks who read papers, go to a science forum.
Here you get opinions from the downtrodden and stricken.
Such is life!
Darwin’s Dilemma = The more educated a human gets, the more he/she is drawn to fables..
The fact that the seam is not explained by the deposition of biological matter is not evidence that the world was created by God 10,000 years ago. The better explanation is that coal and oil are not biological in origin. But if you would rather believe that people riding around on camels in the desert 9,900 years ago had a better source of information, that is your right.
I find it hard to believe that God chose to talk to a handful of people 9,900 years ago, yet has not talked to anyone else since, except Joseph Smith and L. Ron Hubbard. I also don't believe that God is going to lie to us all by creating fossils that look like they are older than 10,000 years old, and stars that are over 10,000 light years distant, just to fool us.
I just don't understand how the theory of evolution calls into question the existence of God. One can believe in both. Perhaps God has left us all the clues to understand who were are and where we came from as part of the path that we are to follow. That he wants us to realize that we are only part of the story, not the end. Remember He created the universe, no? The laws that govern it are his, no? So how does the theory of us evolving from a single cell organism into a human diminish God, or his "gifts"? It doesn't.
I have personally collected and obtained radiocarbon dates older than that.
How do you explain those?
Herein lies the rub: Scientists have already proven that the universe is much much older than your simplistic statement, but, if somehow, it can be absolutely proven that the universe is 10,000 years old, and its a testable fact, then scientists would accept the data. Creationists will never accept any data that is in conflict with their beliefs. So, you have your unflinching dogma, which does not allow you to think in a rational way, even in the face of overwhelming evidence. If you want to live a live of pure ignorance, go ahead, I hope you enjoy it.
It's impossible to summarize these things and the work done by the scientists in these brief press releases, but there's a lot of people who have never read an actual scientific paper in their lives and get the impression that this is all there is.
But yet you feel comfortable summarizing a persons entire life, and their accumulated knowledge therein, by one or two posts on this thread.
I've read plenty of scientific papers, and if in this case, all you can squeeze out of those years or decades of intensive research are mere speculations, then there can't be much substance to the work itself.
Could be that is exactly what these so called illiterates are opining about.
But where are my manners. I've injected myself in a conversation that is clearly outside of my class. My apologies, and please do carry on...
My word, have the unwashed masses dared to voice their uneducated opinions? Dear me, these peasants have no business stepping out of their place. They really should leave the deep thinking to their betters. Pass the grey poupon, would you?
Typical CS b.s. You are the most self-absorbed snob I have ever encountered on this forum. You always insist that anyone who disagrees with you is an ignorant neanderthal, who is so blind to science that they still believe the world is flat. To you, anyone who believes that in order for something to be, it must have been created, is nothing more than a blind fool, who ignores all science. You are beyond arrogant. Evolution is your religion, and it is YOU who is blind to evidence to the contrary. You can accept any fantastic tale, if it's part of your particular dogma, and you quickly revile any poster, who submits any evidence to the contrary, as an idiot. Scrutinize that.
542 MILLION yrs ago....and my friend questions God because he didn't get instant results....
Heh...LOL I like that!
There you go again.
"Life appeared due to, due to.... oxygen - yeah, that's the ticket."
A couple questions. How could there be free iron in the atmsphere? What form would/could it have existed in? Where did the oxygen come from to bind with the iron?
My understanding is that the majority of the oxygen that exists in the atmosphere today has it's source in the oceans. Were the bacteria in the anaerobic conditions of the oceans of the time capable of producing it; were they capable of photosynthesis? If that was the case, the oceans would have been oxygenated before the atmosphere. How could the atmosphere been oxygenated first?
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