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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.
There is evidence of a mass extinction of bony fishes at a fossil site immediately above the K–Pg boundary layer on Seymour Island near Antarctica, apparently precipitated by the K–Pg extinction event; [90] [91] the marine and freshwater environments of fishes mitigated the environmental effects of the extinction event. [92]
"The properties that are visible to selection and evolution in local populations—the extent to which an organism is suited to life here and now" become irrelevant to survival prospects in mass extinction times. "Survival or extinction in mass extinction episodes determines the large-scale shape of the tree of life".
Ceballos pointed to the extinction of the passenger pigeon, which was the only species in its genus, as an example of how losing a genus can have a cascading effect on a wider ecosystem.
"Now, here, you see, it takes all the running you can do, to keep in the same place." — Lewis Carroll [4]. In 1973, Leigh Van Valen proposed the hypothesis as an "explanatory tangent" to explain the "law of extinction" known as "Van Valen's law", [1] which states that the probability of extinction does not depend on the lifetime of the species or higher-rank taxon, instead being constant ...
The mean time between major impacts is estimated to be at least 100 million years. During the last 540 million years, simulations demonstrated that such an impact rate is sufficient to cause five or six mass extinctions and 20 to 30 lower severity events. This matches the geologic record of significant extinctions during the Phanerozoic Eon ...
The "Shiva Hypothesis": Impacts, Mass Extinctions, and the Galaxy, by Rampino and Haggerty; The Shiva hypothesis: impacts, mass extinctions, and the Galaxy, by Rampino, M. R. The correlation between mas extinctions and impacts of near-Earth objects. The review of Shiva hypothesis, by Yang Su, Yi Xia and Yanan Zhang.
Artist's rendering of the Chicxulub asteroid entering Earth's atmosphere 66 million years ago, triggering events that caused a mass extermination. Roger Harris/Science Photo library via Getty ...