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Wednesday, May 20, 2009

Cambrian explosion changed ocean chemistry

"A little more than 500 million years ago, something put the evolutionary pedal to the metal, and the stately, subdued pace of animal life on Earth revved up. Alongside this spurt in speciation — known as the Cambrian explosion — came a jump in the concentration of sulphate in the world's oceans."

"It hasn't been clear why," says Don Canfield of the University of Southern Denmark in Odense. But Canfield and his collaborator, James Farquhar of the University of Maryland in College Park, have a theory to explain it. It's a murky story with a moral: never underestimate the power of a scum-sucking, ocean-bottom worm."

"The planet has long been seen as a driver of evolution. But this, say Canfield and Farquhar, is an important example of how animals, too, can create a global geochemical signal that, in turn, twists evolution's corkscrew. "The Cambrian explosion needs to be viewed as not the consequence of geochemical perturbations, but the cause of them," says Nick Butterfield of the University of Cambridge, UK, who was not affiliated with the study."

Before these sea-floor animals began their steady churn, sulphate — arriving in seas in the run-off from rivers — would largely be turned into hydrogen sulphide by bacteria living in the ocean floor. The sulphide would then be converted to pyrite (FeS2), which, once buried, removes the sulphate from the system. Once bioturbation turned on, however, oxygen in the deep ocean could mix more freely with the sediments, allowing bacteria and other processes to recycle pyrite and turn it back to sulphate. This excess sulphate would have reached a saturation point, giving rise to the formation of gypsum deposits — a mineral that, along with sulphate levels, also happened to rise in the rock record around this time.

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According to this website: "The Cambrian Period occurred 543-490 million years ago.The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears. It was once thought that the Cambrian rocks contained the first and oldest fossil animals, but these are now to be found in the earlier Vendian strata."

"Almost every metazoan phylum with hard parts, and many that lack hard parts, made its first appearance in the Cambrian. The only modern phylum with an adequate fossil record to appear after the Cambrian was the phylum Bryozoa (Bryoza were "moss animals," and aquatic organisms, living for the most part in colonies of interconnected individuals. A few to many millions of these individuals may form one colony. Some bryozoans encrust rocky surfaces, shells, or algae. (source:

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Thoughts worth thinking about

"Our subconscious minds have no sense of humor, play no jokes and cannot tell the difference between reality and an imagined thought or image. What we continually think about eventually will manifest in our lives."-Sidney Madwed

Laws alone can not secure freedom of expression; in order that every woman and man present their views without penalty, there must be spirit of tolerance in the entire population.- Albert Einstein Too often we underestimate the power of a touch, a smile, a kind word, a listening ear, an honest compliment, or the smallest act of caring, all of which have the potential to turn a life around. - Leo Buscaglia

A person's true wealth is the good he or she does in the world. - Mohammed

Our task must be to free ourselves... by widening our circle of compassion to embrace all living creatures and the whole of nature and its beauty. -Albert Einstein

The best way to find yourself, is to lose yourself in the service of others. - Ghandi

The unselfish effort to bring cheer to others will be the beginning of a happier life for ourselves. - Helen Keller

Aim for success, not perfection. Never give up your right to be wrong, because then you will lose the ability to learn new things and move forward with your life. Remember that fear always lurks behind perfectionism. Confronting your fears and allowing yourself the right to be human can, paradoxically, make yourself a happier and more productive person. - Dr. David M. Burns

Life is as dear to a mute creature as it is to man. Just as one wants happiness and fears pain, just as one wants to live and not die, so do other creatures. -His Holiness The Dalai Lama

Mankind's true moral test, its fundamental test (which lies deeply buried from view), consists of its attitude towards those who are at its mercy: animals. And in this respect mankind has suffered a fundamental debacle, a debacle so fundamental that all others stem from it. -

Milan Kundera, The Unbearable Lightness of Being

The worst sin towards our fellow creatures is not to hate them, but to be indifferent to them. That's the essence of inhumanity. -George Bernard Shaw

Ego's trick is to make us lose sight of our interdependence. That kind of ego-thought gives us a perfect justification to look out only for ourselves. But that is far from the truth. In reality we all depend on each other and we have to help each other. The husband has to help his wife, the wife has to help the husband, the mother has to help her children, and the children are supposed to help the parents too, whether they want to or not.-Gehlek Rinpoche Source: "The Best Buddhist Writing 2005 pg. 165

The hostile attitude of conquering nature ignores the basic interdependence of all things and events---that the world beyond the skin is actually an extension of our own bodies---and will end in destroying the very environment from which we emerge and upon which our whole life depends.