Ordovician Period
485-444 million years ago
About this Period
First vertebrates and great marine biodiversity
Detailed Overview
The Ordovician period saw a remarkable diversification of marine life, including the first vertebrates (fish), and the rise of the first animals to colonize the land (possibly arthropods). This period featured the Earth's first major mass extinction event, the Ordovician-Silurian extinction, which eliminated about 85% of marine species. The period was characterized by high sea levels, warm climates, and the formation of many marine limestone deposits.
