Llandovery

System (period)	Series	Stage (age)	Lower boundary, Ma
Devonian	Lower	Lochkovian	419.2±3.2
Silurian	Pridoli		423.0±2.3
	Ludlow	Ludfordian	425.6±0.9
		Gorstian	427.4±0.5
	Wenlock	Homerian	430.5±0.7
		Sheinwoodian	433.4±0.8
	Llandovery	Telychian	438.5±1.1
		Aeronian	440.8±1.2
		Rhuddanian	443.8±1.5
Ordovician	Upper	Hirnantian	older
Subdivisions and "golden spikes" according to IUGS as of September 2023

The Llandovery marks the start of the Silurian period. It lasted from about 443 to 433 million years ago. It follows the massive Ordovician-Silurian extinction event. Which lead to a change in biodiversity and ecosystems.

Large reefs started building in this time period and ocean temperatures were rising. Which is thought to have lead to a bleaching in coral due to killing their photo symbionts. The Llandovery epoch came to an end when the Ireviken event occurred. It removed 50% of trilobite species, and 80% of the global conodont species.

Beginning of Silurian

The end of the Ordovician-Silurian extinction event occurred when melting glaciers caused the sea level to rise and eventually stabilize. Due to this the Silurian communities were initially less complex and broader niched. Large endemic faunas replaced those that were amongst the most cosmopolitan in the Phanerozoic.

Subdivisions

It is characterized into three stages: the Rhuddanian, Aeronian and Telychian.

Paleobiology

The earliest known vascular plants are known from the middle Silurian. There are also spores known from China and Pennsylvania.

The earliest known land animal Parioscorpio venator, which was described in 2020. It was thought to be a scorpion but is now thought to be an unrelated marine arthropod.

Ireviken Event

The Ireviken event was the first of several extinction events during the Silurian.