CALCIUM

[Mike Smith Cosmos]

Can anyone explain all this in terms of CALCIUM ?

 

 

 

 

http://www.newscientist.com/article/mg21829210.400-missing-rock-fuelled-cambrian-explosion-of-life.html?full=true

Missing rock fuelled Cambrian explosion of life

 21 June 2013 by Robert Gaines and Shanan Peters

 Magazine issue 2921.

 For similar stories, visit the The Big Idea and Evolution Topic Guides

The Great Unconformity – a billion years' worth of missing rock strata – could explain the origin of animal life

LIFE on Earth experienced a singular revolution just over 500 million years ago. In a geological blink of an eye, most groups of the animal kingdom appeared in the Earth's oceans and then diversified. The acquisition of skeletons, the advent of predation and the rise of complex ecosystems all occurred in what's known as the Cambrian explosion of marine animals.

Life took such a giant leap forward in abundance and complexity during the Cambrian that the rock record itself was indelibly changed. Long before geologists knew the precise age of the Earth, they could divide its history into two parts: the first 4 billion years, known simply as the Precambrian, followed by the Phanerozoic, meaning "visible life", which includes the Cambrian right up to today.

Evolutionary change isn't supposed to happen so abruptly, at least not according to Charles Darwin. "Darwin's dilemma" over the Cambrian explosion was explained away in his On the Origin of Species as an artefact of an incomplete geological record, one that failed to preserve fossils of a long Precambrian history of slow-paced animal evolution. A century and a half of study has shown that Darwin was right – animals do indeed have a Precambrian origin. A fossil record of that long history of simple bodies and behaviours has now been uncovered, proving that the Cambrian explosion was a real evolutionary phenomenon that needed to be explained.

As is the case with any great mystery, many different hypotheses have been proposed for the long lag between the first appearance of simple animals and their eventual diversification during the Cambrian. Perhaps the Cambrian explosion's long fuse reflects the time it took to evolve the genes needed to control the formation of complex, differentiated bodies? Animals also require oxygen to power their large bodies and active lifestyles, but concentrations of oxygen in Earth's atmosphere are thought to have been rather low during much of the Precambrian,

so perhaps the Cambrian explosion couldn't happen until atmospheric oxygen topped some critical threshold? Or maybe predation was an innovation that required a long time to evolve, but once in place, escalated via natural selection to the fast-paced, eat-or-be-eaten Phanerozoic world?

We have a new hypothesis to add to the mix. We propose that a geological phenomenon was a trigger for the explosion of animal life (Nature, vol 484, p 363). Although our hypothesis is just another in a long list of non-mutually exclusive potential explanations it does, literally, stand out: the geological record of the transition from the Precambrian to the Cambrian is obvious, even from a mile away.

If you stand on the rim of the Grand Canyon and look down to the bottom you can easily distinguish the "Great Unconformity", so named by the explorer and geologist John Wesley Powell in 1869 during his epic trek down the Colorado river. As implied by the name, the Great Unconformity is a juxtaposition of two different types of rock of very different geologic ages along a prominent surface of erosion. This surface represents mind-boggling amounts of "missing" time in the rock record. In many places more than 1 billion years is missing, which is twice the duration of the entire history of animal life on Earth. In the Grand Canyon, younger Cambrian sedimentary rocks deposited on the Earth's surface sit directly on top of much older Precambrian rocks, many of which formed deep in the Earth's crust.

The ultimate cause of this gap remains a mystery. What is clear, though, is that over tens or even hundreds of millions of years before the Cambrian, the uppermost rocks of the continents were stripped away, exposing underlying crystalline basement rocks. This process of continental denudation occurred over a vast area. Much of North America, from California to New York State has a Great Unconformity similar to that in the Grand Canyon, and geologists have reported similar features on other continents as well.

How might the formation of the Great Unconformity be responsible for the Cambrian explosion? We think it comes down to changes in seawater chemistry. These were brought about by the large-scale erosion and chemical weathering of exposed crystalline rock over an area so large there has been nothing like it in the past 1 billion years of Earth history. When carbon dioxide-bearing, slightly acidic rainwater fell on these basement rocks, calcium, magnesium, phosphate and

bicarbonate ions, silicon dioxide and more were liberated and carried into the oceans.

One hallmark of the Cambrian explosion is the widespread acquisition of mineral skeletons by a number of different animal groups involving several types of minerals, such as the silica shells of microscopic organisms called radiolaria, and the calcium carbonate shells of now-extinct arthropods called trilobites. We propose that the origin of biomineralisation – the ability of organisms to make these minerals – was a biological response to changes in seawater chemistry. These changes were caused by the last stages in the formation of the Great Unconformity, when the sea spread over the continents. The action of waves over the weathered basement rocks further eroded the surface, exposing fresh mineral surfaces and causing an increased flux of the ions used in biomineralisation to the ocean.

The weathering products of crystalline rocks don't just end up in biominerals, they also end up in sediments such as limestone. It has long been known that sediments formed in the Cambrian have an abundance of these minerals precipitated from seawater, which provides evidence for our hypothesis.

We suspect that the elevated concentration of ions in seawater effectively lowered the evolutionary barrier for biomineralisation. Today, most organisms invest energy in creating biominerals because hard body parts are so ecologically and evolutionarily advantageous. But evolution couldn't "foresee" how useful biominerals would be when shaped into the teeth, claws and shells we know today. Instead, we think the ion influx promoted by the last stages in the formation of the Great Unconformity may have lowered the energy barrier to biomineralisation or caused biominerals to appear as metabolic by-products. The usefulness of these new raw materials meant that natural selection could quickly take over.

Was the formation of the Great Unconformity directly responsible for the Cambrian explosion? More work needs to be done, particularly with respect to the detailed timing of biomineralisation and the transgression of the sea over vast areas of dry land, and also on the actual biological consequences of our proposed chemical weathering flux. However, one thing is clear: the physical geological record of the Precambrian-Cambrian transition is just as remarkable as the Cambrian explosion, and we now think the two are causally linked.

This article appeared in print under the headline "The great leap forward"

Profile

Robert Gaines is a geologist at Pomona College, Claremont, California, researching extraordinary fossil preservation. Shanan Peters is a geologist at the University of Wisconsin-Madison. This essay is based on a lecture they gave about the Cambrian explosion at the 2013 meeting of the Geological Society, London  From issue 2921 of New Scientist magazine, page 30-31.

 

 

Thanks . Mike

 

 

 

 

IS THIS WHAT ITS ALL ABOUT .

 

A glut of calcium (among other minerals ) was dissolved over a period of 1 billion years from deep seated rock and available en mass at the Pre-cambrian/cambrian border period and thus available in the SEA for the construction of spines, teeth, shells, bones , Skulls etc.

 

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Edited June 24, 2013 by Mike Smith Cosmos

[Essay]

TINY ENGINES OF EVOLUTION

http://www.scientificamerican.com/article.cfm?id=tiny-plants-that-once-ruled-the-sea

Tiny Plants That Once Ruled the Seas [Preview]

"Around 250 million years ago animals in the seas began to diversify with gusto. Remarkably, the evolution of minute plants known as phytoplankton probably powered that dramatic explosion"

“If you could hop onboard a time machine and visit the earth as it was 500 million years ago, during the Paleozoic era, you'd be forgiven for thinking you had traveled not to another time period but to another planet altogether.”

....

“But after the Permian mass extinction wiped out the vast majority of marine life, including most of the green algae, new kinds of phytoplankton appeared, starting with coccolithophores, so named for the calcium carbonate shells, or “coccoliths,” they secrete, possibly for protection.” –p.44 Scientific American, June 2013

 

http://www.nature.com/scientificamerican/journal/v308/n6/box/scientificamerican0613-40_BX1.html

I know this isn't the right period (Permian), but the process is similar, plus their chart goes back to the Cambrian.

 

~

Edited June 24, 2013 by Essay

[Mike Smith Cosmos]

 

TINY ENGINES ..............................

 

Yes but surely we can not just talk of 1,000,000,000 years of rain fall, washing away into the sea countless giga tons of chemicals

 

and then go and make a cup of tea.

 

. This is mind blowing !

 

Mike.

Edited June 24, 2013 by Mike Smith Cosmos

[Mike Smith Cosmos]

A billion years (1,000,000,000 years of rain fall) [TWICE THE LENGTH OF ALL THE REST OF GEOLOGICAL HISTORY FROM CAMBRIAN 500,mya UNTILL TODAY ] , washing away into the sea countless giga tons of chemicals

 

. This is mind blowing !

 

 

. Perhaps .. have I picked it up Wrong !

Edited June 26, 2013 by Mike Smith Cosmos

[EdEarl]

I am mostly ignorant of geology, and do not understand what you are looking for. But, a bit of research discovered that some of the period between 500 Ma to 1,000 Ma may have been a snowball earth.

[Mike Smith Cosmos]

I am mostly ignorant of geology, and do not understand what you are looking for. But, a bit of research discovered that some of the period between 500 Ma to 1,000 Ma may have been a snowball earth.

As per message :

 

 

Maybe I am wrong, but I think a snowball Earth would affect calcium in two ways. First, it might scrape it off igneous rock. Second, it would prevent rain from eroding rocks.

 

I don't actually Know. I have this woolly picture ( of the Early Pre Cambrian ) of boiled up mantle as some form of volcanic soup of all the chemical elements, trying to crystalise out into happy molecules that the chemicals have crystalised out into., Then what happens .?? Do they get rained on or frozen on for a billion years to turn into a Sea Soup ?

 

. Maybe some kindly Geology Expert will respond ,to put me out of my misery .

 

 

Edited June 27, 2013 by Mike Smith Cosmos