Ordovician

The Ordovician period, occurring about 485 to 444 million years ago, was a significant chapter in Earth's history marked by diverse marine life and major geological changes. During this time, oceans flourished with various invertebrates like trilobites, brachiopods, and the first coral reefs. It saw the rise of early fishes and a dramatic increase in biological diversity known as the "Ordovician Radiation." The period ended with a major ice age and mass extinction event that wiped out many marine species. Overall, the Ordovician played a crucial role in shaping the development of complex marine ecosystems.