Great mass extinction | Number | Date extinction occurred | Cause of extinction | Loss of life |
---|---|---|---|---|
Ordovician-Silurian extinction | 1st | Approximately 439 million years ago | Fluctuations in sea level; extensive glaciations; global warming | ‘Approximately 25% of the families and nearly 60% of the genera of marine organisms were lost. |
Late Devonian extinction | 2nd | Approximately 364 million years ago | Global cooling after bolide impacts may have been responsible | ‘22% of marine families and 57% of marine genera, including nearly all jawless fishes, disappeared.’ |
Permian-Triassic extinction | 3rd | Approximately 251 million years ago | Causes are debated. The leading candidate is flood volcanism. This led to profound climate change. The volcanism may have been initiated by a bolide impact | ‘95% of all species (marine as well as terrestrial) were lost, including 53% of marine families, 84% of marine genera, and 70% of land plants, insects, and vertebrates.’ |
End Triassic extinction | 4th | Approximately 199 to 214 million years ago | ‘Opening of the Atlantic Ocean by seafloor spreading related to massive lava floods that caused significant global warming.’ | ‘Marine organisms were most strongly affected (22% of marine families and 53% of marine genera were lost), but terrestrial organisms also experienced much extinction.’ |
Cretaceous-Tertiary extinction | 5th | Approximately 65 million years ago | Causes are debated. Possible causes include a giant asteroid impact in the Gulf of Mexico and climatic changes resulting from volcanic floods in India | ‘16% of families, 47% of genera of marine organisms, and 18% of vertebrate families were lost.’ |