200 million years missing from the story? The study that challenges history

A new study challenges the assumption that the first animals appeared about 574 million years ago. A combination of genetic data, chemical markers, and fossil sites suggests they may have emerged as early as 700 to 800 million years ago, meaning before or during extreme ice ages.

A new study casts doubt on the accepted assumption that the first animals appeared about 574 million years ago. Researchers argue that the story may have begun much earlier, as the first animals were likely tiny, soft-bodied creatures without bones or shells, leaving behind few easily identifiable fossils. The researchers re-examined the assumption that if a site rich in tiny fossils contains no animals, they had not yet appeared. As an example, they point to the Kheseen fossil site in Mongolia, dated to about 550 million years ago—a period when animals are known to have existed—yet no animal fossils were found there. Instead of relying solely on what is absent from ancient rocks, the researchers combined genetic data, chemical markers, and fossil sites in Australia, Norway, and Arizona, dated to about 850 to 730 million years ago. This combination led to an estimate that the first animals may have appeared 700 to 800 million years ago—before or during the "Snowball Earth" period, a series of extreme ice ages that began about 720 million years ago.