GEOLOGY

Detailed explanation-1: -About 445 Million Years Ago: Ordovician Extinction Its major casualties were marine invertebrates including brachiopods, trilobites, bivalves and corals; many species from each of these groups went extinct during this time.

Detailed explanation-2: -These first steps toward life on land were cut short by the freezing conditions that gripped the planet toward the end of the Ordovician. This resulted in the second largest mass extinction of all time, wiping out at least half of all marine animal species about 443 million years ago.

Detailed explanation-3: -Around 443 million years ago, 85% of all species on Earth went extinct in the Ordovician-Silurian extinction.

Detailed explanation-4: -Nearly 500 million years ago in the late Ordovician period, a mass extinction wiped out 85% of marine species.