New, "pristine" fossils reveal secrets of Cambrian explosion

Scientists work to dig up fossils at the Qingjiang biota in China.
Digging up a Qingjiang fossil on a bank of the Danshui River, Hubei Province, China. Photo: Dong King Fu

On the banks of the Danshui River in China, scientists have unearthed a treasure trove of pristine fossil remnants from one of the most important periods in the history of life on Earth: the Cambrian explosion.

The big picture: The Cambrian explosion, which occurred a little more than 500 million years ago and lasted for about 40 million years, is the period when nearly all the major groups of multicellular life forms currently on Earth first appeared. It was a period of frenzied evolutionary development and biodiversity buildup, mainly in the world's oceans.

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Artist depiction of what marine life looked like during the Ediacaran period. Credit: Peter Trusler

After about 3 billion years of Earth being dominated by microbes, complex, soft-bodied organisms (up to 3 feet long) emerged in the deep oceans.

Combining evidence from the fossil record with insights from animal physiology, scientists have now put forward a new explanation for why this occurred about 570 million years ago, during a period known as the Ediacaran.