The Dresbachian extinction
Trilobite faunas collapse worldwide as oxygen-poor water floods the shelves.
- When
- Known to
- ± 3 million years
- Era
- Cambrian, Paleozoic
Around 502 million years ago a major turnover eliminates a large share of trilobite families, along with brachiopods and conodonts. Like the other Cambrian crises it is associated with the spread of anoxic water onto continental shelves. Repeated events of this kind mean Cambrian marine communities were reassembled several times over before the Ordovician.