500 million years ago, a series of mass extinctions at the Cambrian-Ordovician boundary eliminated many brachiopods and conodonts, and severely reduced the number of trilobite species.
440 million years ago, at the Ordovician-Silurian transition, a double extinction occured, probably as the result of a period of glaciation. As the seas retreated the marine habitats changed drastically, causing the first die-off, then another occured between 500 thousand and a million years later when sea levels rose rapidly.
About 365 million years ago, in the transition from the Devonian to the Carboniferous period, about 70% of all species were eliminated. This was not a sudden event; evidence suggests that the extinctions took place over a period of some three million years.
225 million years ago, in the transition from the Permian period to the Triassic, 90-95% of all marine species died out. This was the largest extinction event in Earth's history.
195 million years ago, at the transition from the Triassic to the Jurassic, about 20% of all marine families in Earth's oceans were wiped out, as well as most non-dinosaurian archosaurs, most therapsids, and the last of the large amphibians.
65 million years ago, the Cretaceous-Tertiary extinction event killed about 50% of all species died out, including the dinosaurs.
Some people claim that we are living in the middle of another, man-made extinction event right now. However, humanity's effects are trivia compared with the extinction events shown in the fossil record.
See also
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