When were conditions first right for preserving animal fossils?

Analysis of Burgess Shale-like rocks reveal certain types of clay increase chances of soft-bodied fossil preservation

When did the first animals appear on Earth? If the fossil record is to be believed, the first animals evolved about 570m years ago and proliferated rapidly during the Cambrian explosion, approximately 539m to 485m years ago. But if you follow the molecular clock, which uses the rate at which genes accumulate mutations to extrapolate living animals back to their oldest common ancestor, animals probably first evolved about 800m years ago.

Now researchers have taken a different approach and asked when were conditions right for preserving animal fossils? The first animals are thought to have lacked mineral-based shells or skeletons, and would have needed exceptional conditions to be fossilised, akin to the famous 500m-year-old Burgess Shale deposits in the Canadian Rockies.

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