The 'Age of Fishes' began with mass death, fossil database reveals

Some 445 million years ago, life on Earth was forever changed. During the geological blink of an eye, glaciers formed over the supercontinent Gondwana, drying out many of the vast, shallow seas like a sponge and giving an "icehouse climate" that, together with radically changed ocean chemistry, ultimately caused the extinction of about 85% of all marine species—the majority of life on Earth.