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Oxygen boost aided carnivore evolution in Cambrian explosion

Atmospheric change and rise of predators caused burst in complexity of life

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3:07pm, July 29, 2013

ANIMAL REVOLUTION  A rise in oxygen may have allowed carnivores to evolve, a new study of polychaete worms (one shown) suggests. The origin of predators may have then kicked off an arms race that triggered the Cambrian Explosion more than half a billion years ago.

A rise in oxygen more than half a billion years ago paved the way for the origin of the first carnivores. The meat eaters in turn triggered the Big Bang of animal evolution, researchers argue.

The major groups of modern animals — everything from insects to creatures with a backbone — popped up 540 million to 500 million years ago in a proliferation known as the Cambrian Explosion. Fossil and molecular evidence hint that the most primitive animals appeared a couple hundred million years earlier, leading scientists to wonder about the cause of the lag.

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