Geological time and extinction

The precambrian era

4.6 bya to 540 million years ago. life originate and over which enough atmospheric oxygen accumulated allowing aerobic life to establish.

the cambrian explosion

a period of roughly 20 million years that began roughly 540 million years ago. It marks the beginning of the Paleozoic era. Most modern animal phyla are distinct at this time.

End Permian mass extinction

252 million years ago. marks the boundary between the paleozoic and mesozoic eras. Also known as the great dying, the biggest mass extinction in earth’s history.

End cretaceous mass extinction

60 million ago. marks the end of the mesozoic era and the start of the cenozoic era. this led to the extinction of non-bird dinosaurs and nearly all tetrapod over 25 kg. After the cretaceous extinction, mammals and flowering plants diversified.

mass extinction

A catastrophic event that occurred relatively quickly, resulting in a dramatic loss of species, genera and families