1. The earth experienced five mass extinctions in history. There have been five extinctions in the history of the earth, namely, the first extinction from the end of Ordovician to the beginning of Silurian, the Persian Paleozoic extinction, the third extinction from the end of Permian to the beginning of Triassic, the fourth extinction from the end of Cretaceous, and the fifth extinction from Neogene to modern times.

2. The earth experienced five mass extinctions. The first time: it happened at the end of Ordovician 400 million years ago. Event: About 85% of species became extinct. The first extinction was also called the Ordovician extinction.

3. The earth mainly experienced five mass extinctions, the first one happened at the end of Ordovician 400 million years ago; The second Late Devonian 6.5 billion years ago; The third time happened at the end of Permian 500 million years ago; The fourth time occurred in the late Triassic period 200 million years ago; The last time happened at the end of Cretaceous 65 million years ago.

Before this, there were five mass extinctions on the earth. The last mass extinction occurred in the Cretaceous-Tertiary period 63 million years ago. Scientists believe that it was caused by an asteroid hitting the earth. Dinosaurs disappeared from the earth and mammals appeared.