Ordovician-Silurian extinction event

The Ordovician-Silurian extinction event, occurring around 445 million years ago, was one of the largest mass extinctions in Earth's history, wiping out about 85% of marine species. It was likely caused by a combination of climate changes, such as global cooling and glaciation, which lowered sea levels and disrupted habitats. These environmental shifts drastically affected marine life, especially organisms living in shallow seas. The event marked a significant reset in Earth's biodiversity and took millions of years for life to recover fully.