The Sinsk event
The first mass extinction of animal life kills roughly half of all species and ends the Cambrian radiation.
- When
- Known to
- ± 2 million years
- Era
- Cambrian, Paleozoic
About 513 million years ago widespread ocean anoxia removes around half of standing generic and species diversity, hitting reef builders and shallow-water communities hardest. It is now recognised as the first Phanerozoic mass extinction, and it marks the end of the canonical Cambrian Radiation. Several groups — archaeocyaths among them — never recover their former diversity.