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The natural world. Looking pretty for 3.5b years.

Catastrophic Evolution

Author: Guest Writer/Thursday, February 7, 2013/Categories: Uncategorized

Natural catastrophes happen---just think Pompeii or Ubar, two cities of the ancient world that disappeared in dual catastrophes that became legends until being re-discovered in the 18th and 20th Centuries. Massive random events can be caused by earthquakes, volcanoes, tsunamis, plagues, or even asteroids. Besides their destructive force, they also produces prime opportunities for natural selection to being working on the survivors. A perfect example is the evolution of mammals at the end to the Age of Dinosaurs who then ruled the earth.

Approximately 65 million years ago an asteroid 5 miles wide slammed into the Earth in what is now the Yucatan Peninsula and caused the extinction of 75 percent of life on Earth. Known as the Chicxulub impactor, named for the Mexican town where tell-tale meteorite residues of the rare-earth mineral iridium were first discovered, it brought the Cretaceous period to an end. The dinosaurs disappeared shortly thereafter in an geological blink of time.

When the meteor impact was first proposed in 1980, it was considered a heretical theory but recent discoveries now reported in Science Magazine have shown the durability of the early analysis. National Public Radio aired a nice summary of the latest research just published.

Chicxulub Impactor in early Yucatan, Mexico  (credit: NPR)

The other impact of the Chicxulub meteor was
to unleash the power of natural selection and evolution to allow entire new plants and animals to repopulate landscapes devastated by the catastrophe. We should be thankful for this as the evolution of mammals, of which we belong, then began. In the Science report, the researchers described their use of vast databases of fossils and other biological data, as well as DNA evidence, to re-create the hypothetical ancestor for all mammalian species. Everything from whales, chimpanzees, dogs, rodents, and humans subsequently evolved from a humble shrew-like creature that survived the catastrophic end of Cretaceous event. The creature is now recognized as the progenator for all subsequent placental mammals. It is also another example for the power of  Big Data to analyze significant patterns from large data sets.

Early Mammalian Ancestor (credit: AAAS)

As Jonathan Block, one of the lead authors, commented:
"This gives us a new perspective of how major change can influence the history of life, like the extinction of the dinosaurs. This was a major event in Earth's history that potentially then results in setting the framework for the entire ordinal diversification of mammals, including our own very distant ancestors."

While catastrophes do cause big disruptions in the standing order, we are an evolutionary beneficiary of one such event. As the old adage goes: From Tiny Acorns, Mighty Oaks Doth Grow.




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