Silurian Bio-Events

In the history of Silurian biota and ecosystem as a whole no “big” catastrophes occurred like the one at the Ordovician-Silurian boundary. Yet it was not a quiet period either. There were established 15 more or less remarkable bio-events, among others the most severe extinction of conodonts and acritarchs in the very beginning of the Wenlock (Ireviken Event), the Great Crisis or lundgreni Event among graptolites in the Homerian and the middle Ludfordian Event comprising many lineages of vertebrates, graptolites, conodonts and corals. Most remarkable diversity rises of the Silurian biota were in the late Rhuddanian, in the Telychian and in the early Gorstian. Both extinctions and originations were in good correlation with the global sea-level curve, but the effect has to be interpreted as an integrated process partly triggered by development of early Silurian glaciation and climate in general.