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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 fall in the diversity and abundance of multicellular organisms .
Luis Walter Alvarez, left, and his son Walter, right, at the K–T Boundary in Gubbio, Italy, 1981. The Alvarez hypothesis posits that the mass extinction of the non-avian dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth.
Deeper in time, a mass extinction event that ended the Devonian Period, a geological era when life thrived on land for the first time, was also attributed to a hyperthermal event likely triggered ...
The study also emphasized that deflection, as opposed to destruction, can be a safer option, as there is a smaller likelihood of asteroid debris falling to Earth's surface. The researchers proposed the best way to divert an asteroid through deflection is adjusting the output of neutron energy in the nuclear explosion. [93]
The Cretaceous–Paleogene (K–Pg) extinction event, [a] also known as the K–T extinction, [b] was the mass extinction of three-quarters of the plant and animal species on Earth [2] [3] approximately 66 million years ago. The event caused the extinction of all known non-avian dinosaurs.
However, this hypothesis has been criticised on the grounds that the multispecies model produces a mass extinction through indirect competition between herbivore species: small species with high reproductive rates subsidize predation on large species with low reproductive rates. [152] All prey species are lumped in the Pleistocene extinction model.
The idea of extinction periodicity has been criticised due to the fact that the hypothesis assumes that most or all extinction events have the same cause, when evidence suggests that extinctions are likely the result of a variety of causes that are unlikely to be cyclically induced. [8]
The Lilliput effect, a term coined to describe a phenomenon wherein organisms shrink in size following a mass extinction, affected megalodontid bivalves, [20] whereas file shell bivalves experienced the Brobdingnag effect, the reverse of the Lilliput effect. [21] There is some evidence of a bivalve cosmopolitanism event during the mass ...