The main event Appearance of an abundance of fossils of organisms with hard shells.
The Cambrian Explosion was a relatively short-lived evolutionary event that began in the Cambrian period, about 542 million years ago, during which most of the large phyla of animals emerged, as evidenced by the fossil record.
The Cambrian Explosion was a Cambrian event about 541 million years ago when most of the major animal phyla appeared in the fossil record. It took about 20-25 million years. It led to the divergence of the most modern metazoan phyla
and
. It was the sudden appearance (over 10,000 years) of many different organisms that occurred 540 to 548 million years ago.
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