Date: 488 to 444 million years ago
Probable cause: Glacial and interglacial episodes caused sea levels to rise and fall dramatically, moving shorelines repeatedly. Continental erosion changed atmosphere and ocean chemistry.
Percentage or numbers of organisms which went extinct: 80% Extinct
Main organisms which went extinct:
Trilobites, corals, brachiopods, bryozoans, echinoderms, graptolites, nautiloids, conodonts