Cambrian explosion

The Cambrian explosion describes the geologically sudden appearance of hard-bodied animals in the fossil record, around . This is accompanied by a profound diversification of life on Earth. Prior to around , organisms were on the whole simple, comprised of individual cells occasionally organised into colonies. Over the subsequent 70-80 million years, the rate of evolution would accelerate by an order of magnitude, and the diversity of life would begin to resemble today's.
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