Silurian 443.8 Mya - Named for a Celtic tribe, Silures

First Carbonate Reefs

Earth’s atmosphere developed an effective ozone layer concentration. Generally speaking, the climate stabilized, ending the previous pattern of climatic fluctuations that periodically caused continental glaciations; glacial melting contributed to a substantial rise in global sea level.

Possibly the most remarkable biological event during the Silurian was the evolution and diversification of fish. Not only does this time period mark the wide and rapid spread of jawless fish, but also the appearances of both the first known freshwater fish and the first fish with jaws.