Microfossil spectroscopy dates Earth's first animals

Molecular clock dates for the first animals to walk the Earth don't match the fossil record. Comparing the disparate DNA of two different species and extrapolating how long it would take for them to mutate from a common ancestor suggests animals existed 833-650 million years ago, but the oldest animal fossils discovered so far only date back 580 million years. One explanation is shortcomings in the fossil record—animals did exist, but the rocks and environment were not suitable for fossilization until only 580 million years ago. Now, energy dispersive X-ray spectroscopy and high-resolution infrared spectroscopy have identified the minerals in the mudstones around ancient microfossils, giving insights into their formation suggesting that the right conditions for fossilization existed long before the first animal fossils found so far began to form. The results might also hint at how best to look for evidence of life on Mars.

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