Climate - Extinctions

Early Silurian marine life recovered from a mass extinction during the Late Ordovician, caused by climate change and sea level fall. This mass extinction resulted in the extinction of 26% of all marine invertebrate families and 60% of all marine invertebrate genera.

During the Silurian, several small extinctions and radiative events in the evolution of free-swimming and free-floating organisms appear to be related to fluctuations in sea level. Ten extinction events have been recorded in the Silurian period for hookworms alone, with 52-79% of these planktonic animals extinct. Most of these events corresponded to a drop in sea level.

Acritarchs is a general term for a variety of small microfossils thought to be sporozoites of benthic algae distributed throughout the pelagic zone. Four main transitional periods are known for Silurian acritarch species. Among those coinciding with the high sea level trough, the Llandovery Age and early Ludlow Age transitions are the most extensive.