Life Has Nearly Been Wiped Out Five Times — 'Mass Extinction Exhibition' Underway in Osaka

Explanation

In the roughly 4 billion years since life first appeared on Earth, 'mass extinctions,' in which large numbers of species disappear at once, have occurred five times if counting only the largest-scale events. These are called the 'Big Five.' The special exhibition 'Mass Extinction Exhibition — The Big Five of Life's History' at the Osaka Museum of Natural History (July 17 to October 12, 2026) explores these five great catastrophes using fossils and rocks as 'evidence.'

For example, in the extinction that occurred about 252 million years ago (the end of the Permian period of the Paleozoic era), more than 90% of marine life is believed to have gone extinct. One suspected cause is that massive volcanic activity released huge amounts of carbon dioxide, warming the planet and reducing oxygen levels in the ocean. The extinction that wiped out the dinosaurs about 66 million years ago (the end of the Cretaceous period of the Mesozoic era) is famously theorized to have been triggered by the impact of a giant meteorite.

Such past events can be reconstructed from rocks because geological strata accumulate in chronological order, with the fossils within them recording 'when and what kinds of creatures existed.' The exhibition also features valuable specimens from the Denver Museum of Nature & Science, including the world's first public display of a complete fossil skeleton of a Steller's sea cow, about 6 meters long. Learning about past extinctions also offers hints for thinking about the biodiversity loss occurring today.