The end-Botomian extinction
The first great crash of the Cambrian wipes out reef builders across the world.
- When
- Known to
- ± 3 million years
- Era
- Cambrian, Paleozoic
Around 517 million years ago archaeocyath reef communities collapse, along with many small shelly taxa. It is one of a series of early Cambrian extinctions linked to episodes of ocean anoxia, and reef ecosystems take a long time to recover — archaeocyaths never do. The event shows that the Cambrian radiation was not a smooth ascent but a sequence of booms and severe crashes.