The first animals may be hiding 200 million years before their fossils

A survey of more than 140 exceptionally preserved samples from Mongolia's Kheseen Biota found no definitive animals even though animals are known from elsewhere at that time. That weakens the assumption that an older deposit without animal fossils marks a hard beginning. Using older calibration limits moved a molecular-clock estimate for animal origins to roughly 800–700 million years ago — a model result, not the discovery of an animal that old.