# Ordovician–Silurian extinction event

> mass extinction event at the end of the Ordovician period and the beginning of the Silurian period in the Paleozoic era, around 444 million years ago

**Wikidata**: [Q1065985](https://www.wikidata.org/wiki/Q1065985)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Late_Ordovician_mass_extinction)  
**Source**: https://4ort.xyz/entity/ordovician-silurian-extinction-event


## References

1. [Source](http://stratigraphy.org/ICSchart/ChronostratChart2018-08.pdf)
2. Freebase Data Dumps. 2013