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The geologic record of reefs on Earth

Earth during the Cretaceous Period, 90 million years ago, with reef sites highlighted in red.
Earth during the Cretaceous Period, 90 million years ago, with reef sites highlighted in red.
The geologic history of reefs is interrupted by five major extinction events. During these events, large numbers of the earth's species died out. The best known of these events, at the Cretaceous-Tertiary boundary, was caused by an asteroid or comet impact that eliminated dinosaurs as well as many marine species. Causes of older extinction events are still being studied Each major extinction event eliminated reefs from the world oceans. Following an extinction event, millions of years passed before reefs re-evolved. The newly evolved reef communities often differed in biotic composition from those that preceded them.

Photo Gallery

Earth during the Cambrian Period, 540 million years ago, with reef sites highlighted in red.
© The Field Museum
Earth during the Devonian Period, 370 million years ago, with reef sites highlighted in red.
© The Field Museum
Earth during the Silurian Period, 430 million years ago, with reef sites highlighted in red.
© The Field Museum
Earth during the Permian Period, 260 million years ago, with reef sites highlighted in red.
© The Field Museum
Earth during the Cretaceous Period, 90 million years ago, with reef sites highlighted in red.
© The Field Museum