The Llandoverian Epoch follows the massive Ordovician-Silurian extinction events, which led to a large decrease in biodiversity and an opening up of ecosystems.

The end of the Ordovician–Silurian extinction event occurred when melting glaciers caused the sea level to rise and eventually stabilize.

Nevertheless, a large number of taxa disappeared from the Earth over a short time interval,[7] eliminating and changing diversity.

[6] It has been recommended to place the GSSP at a slightly higher and correlatable level on the Ireviken datum 2, which coincides approximately with the base of the murchisoni Graptolite Biozone.

[12][13] There was some movement to the land during the Llandovery but the earliest known vascular plants (Cooksonia) have only been found in rocks of the middle Silurian.

[2][16] It comprises eight extinction "datum points"—the first four being regularly spaced, every 31,000 years, and linked to the Milankovic obliquity cycle.

Correspondingly, shallow-water reefs were barely affected, while pelagic and hemipelagic organisms such as the graptolites, conodonts and trilobites were hit hardest.