GEOLOGY

Detailed explanation-1: -Mass extinctions are episodes in which a large number of plant and animal species become extinct within a relatively short period of geologic time-from possibly a few thousand to a few million years. After each of the five major mass extinctions that have occurred over the last 500 million years, life rebounded.

Detailed explanation-2: -What causes mass extinctions? Past mass extinctions were caused by extreme temperature changes, rising or falling sea levels and catastrophic, one-off events such as huge volcanic eruptions or an asteroid hitting Earth. We know about them because we can see how life has changed in the fossil record.

Detailed explanation-3: -The largest extinction in Earth’s history marked the end of the Permian period, some 252 million years ago. Long before dinosaurs, our planet was populated with plants and animals that were mostly obliterated after a series of massive volcanic eruptions in Siberia.

Detailed explanation-4: -Cretaceous-Paleogene extinction-66 million years ago The Cretaceous-Paleogene extinction event is the most recent mass extinction and the only one definitively connected to a major asteroid impact. Some 76 percent of all species on the planet, including all nonavian dinosaurs, went extinct.

Detailed explanation-5: -An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms.