The highest seas of the Phanerozoic
Continents drown under shallow water, and marine life gets the largest habitat it will ever have.
- When
- Known to
- ± 10 million years
- Era
- Ordovician, Paleozoic
Ordovician sea level reaches the highest sustained values of the last 540 million years, flooding continental interiors with warm epeiric seas hundreds of kilometres across. That vast expansion of shallow, sunlit, well-oxygenated shelf is the physical setting for the Ordovician radiation. Its later withdrawal, as ice sheets grow, removes the habitat and helps drive the extinction that ends the period.