The Precambrian ends
Four billion years of microbes and mats close, and the fossil record is about to explode.
- When
- Known to
- ± 1 million years
- Era
- Cambrian, Paleozoic
The Ediacaran–Cambrian boundary at 538.8 million years ago is defined by the first appearance of the complex burrow Treptichnus pedum. Behind it lie roughly 88% of Earth's history: the origin of life, oxygen, the eukaryotic cell, sex and the first animals — nearly all of it recorded in chemistry and microfossils rather than visible remains. Ahead lies a fossil record dominated by shells, skeletons and eyes.