The timing of five great extinctions
Over geological time, there are five great extinctions. They are
Period | Time (Million years ago) |
Ordovician | 440 |
Devonian | 370 |
Permian | 252 |
Triassic | 200 |
Cretaceous | 65 |
The time difference between the first to the third is about 188 million year. The Permian great extinction ended the Paleozoic era. The time difference between the third to the fifth is about 187 million year. The Cretaceous great extinction ended the Mesozoic era.
Note that the time differences between the first to the third and the third to the fifth are almost identical. Is this a coincidence? Or is there some internal rhythm of life’s evolution?
