The Late Ordovician mass extinction had occurred around 445 million years ago, and it had ended up killing a whopping 85% of all species.
Earth’s first mass extinction: When anyone thinks of mass extinction on Earth, the first thing they think of is the extinction of dinosaurs about 66 million years ago, likely as an impact of comet or asteroid collision with the Earth. This was the Cretaceous mass extinction. However, before this, there were four other great mass extinctions that the Earth witnessed. According to a report in IE, a paper in Nature Geoscience journal has presented a new reason for the first mass extinction on the Earth, called the Late Ordovician mass extinction. As per the paper, it is likely that the ocean circulation pattern was changed by the cooling climate, and this led to the flow of oxygen-rich water from seas to deeper oceans being disrupted. As a result, marine creatures likely ended up being extinct in large numbers.
The University of California, Berkeley’s Seth Finnegan, who is an author in the study, was cited by the report as saying that the Ordovician sea had then contained not just clams, sponges and snails, but also many other groups like brachiopods, crinoids and trilobites that are either now much less diverse than they used to be or have gone entirely extinct.
The Late Ordovician mass extinction had occurred around 445 million years ago, and it had ended up killing a whopping 85% of all species. After that, the next mass extinction that occurred was the Devonian mass extinction that took place about 375 million years ago and in this event, around 75% of all the species of the Earth had been wiped out. Around 250 million years ago, more than 95% of all species went extinct in the Permian mass extinction, which is also called the Great Dying. Around 80% of the species, including some dinosaurs, of the planet were wiped out about 200 million years ago in the Triassic mass extinction.
The fifth great mass extinction was the Cretaceous mass extinction, known as the event which ended all the non-avian dinosaurs.
Researchers are now also of the view that a sixth mass extinction is taking place currently due to the climate change caused by humans.