"The Great Extinction" & Rise of Modern Species
Our planet has gone through several mass extinction episodes in our 4.5 billion year history: the most recent being the Cretaceous 65 million years ago, which wiped out 70 to 75 percent of the species including the dinosaurs. But the real whopper of mass extinctions was the Permian, about 245 million years ago that wiped out at least 95 percent of the species known from fossil records.
According to a research published in the journal Nature, the mass extinction of the Cretaceous, did not, contrary to conventional wisdom, immediately clear the way for the rise of today’s mammals. This extinction is marked by a point known to geology as the KT boundary, a reddish quarter-inch strata of clay created by an impact from an asteroid that struck the planet with the force of 100 million megatons-that's equal to one Hiroshima-sized bomb for every person on the earth today.
The Nature article points out that the ancestral branches of most mammals, including primates, rodents and hoofed animals, emerged long before the global extinction and survived it more or less intact. But it was not until at least 10 million to 15 million years afterward that the lineages of living mammals began to flourish in number and diversity.
The later burst of mammal evolution, 50 million years ago, coincides with one of the largest and quickest warming events in Earth history — in some places, temperatures increased by 7 °C. This seems to have driven many species extinct, and given others their opportunity to thrive.
One thing is certain from the long history of our planet: 95 percent of all the once living, crawling, swimming, flying, burrowing and walking species are no longer with us. Original post by Casey Kazan.
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