This cooling event occurred during the late Ordovician period, around 445–443 million years ago, and is characterized by a significant global glaciation that led to widespread ice sheets ...

The first of the Big Five mass extinctions transpired about 445 million years ago, marking the boundary between the Ordovician and Silurian periods back when fish and land plants were still ...

A few million years following the period of increased meteor strikes, about 445 million years ago, there was a dramatic decrease in Earth’s global temperatures known as the Hirnantian Age.

Maps of colliding volcanic arcs and continents 0, 250, 300, and 445 million years ago. Modern locations are shown in the top left map. ... going back to the Cambrian period 540 million years ago.