When was the first mass extinction

Answer 1

There have been five mass extinction events. None of the events are considered to be archaeological, as they all occurred prior to the rise of our earliest ancestors, the australopiths or homininians, as well as the first stone tools, the Pre-Mode I tradition, found at the site of Lomekwi 3 in Kenya, which date to c.a. 3.3 million years ago. The five events are:

1. The Ordovician–Silurian extinction event c.a. 450 million years ago.
2. The Late Devonian extinction event, c.a. 360-375 million years ago. One of the proposed causes is an asteroid which struck an area in central Sweden named the Siljan Ring.
3. The Permian–Triassic extinction event, c.a. 252 million years ago. This event is named The Great Dying because it wiped out up to 96% of all sea life and 70% of land-based vertebrate species.
4. The Triassic–Jurassic extinction event, c.a. 201 million years ago. This event killed half the species on Earth. This event was the catalyst that scientists believe lead to the age of the dinosaurs. The probable cause of the Tr-J extinction places was the start of volcanic eruptions in the Central Atlantic Magmatic Province or CAMP.
5. The Cretaceous–Paleogene extinction event c.a. 66 million years ago, resulting in the K-Pg Boundary (archaeologists refer to this as the KT Boundary), consisting of an asteroid which caused volcano eruptions and climate change and brought us from the dinosaur age to the Cenozoic Age, the Age of Mammals. If you are an archaeologist and are excavating and hit the KT boundary, it’s time to stop digging and let the paleontologists take over.

Scientists argue that a sixth extinction event is occurring now, and that human impact on the planet in the form of climate change is accelerating this event.