Life moves into fresh water
Eurypterids and early fish push up rivers and lakes, colonising water that is not the sea.
- When
- Known to
- ± 5 million years
- Era
- Silurian, Paleozoic
The Silurian sees one of the earliest large-scale invasions of non-marine aquatic environments, with eurypterids and jawless fish appearing in freshwater and brackish deposits. Fresh water demands entirely different osmotic regulation from seawater, and solving that problem is a precondition for eventually leaving water altogether. The lineages that later crawl onto land come from these rivers, not from the open ocean.