Mass Extinction Event

A Mass Extinction Event is a species-related event that is an accelerated mass extinction phase that involves rapid and widespread species extinction occurring in under 10 years and represents a critical evolutionary choke point in the history of life.

• AKA: Biotic Crisis, Extinction Crisis, Biodiversity Collapse Event.
• Context:
  • It can typically occur when the conditions of a mass extinction ecosystem change at catastrophic rates far exceeding evolutionary adaptation capability.
  • It can typically result from various mass extinction causal factors, including mass extinction climatic conditions, changes in mass extinction sea levels, mass extinction asteroid impacts, mass extinction volcanic eruptions, and the evolution of new mass extinction competitive species.
  • It can typically result in the loss of most of the mass extinction ecosystem species present in the mass extinction ecosystem.
  • It can typically create an Evolutionary Choke Point that dramatically narrows genetic diversity and viable evolutionary pathways for mass extinction surviving lineages.
  • It can typically function as a major evolutionary branch point where mass extinction selective pressures eliminate many mass extinction evolutionary possibilities while opening mass extinction evolutionary niches for mass extinction surviving species.
  • It can typically reshape global biodiversity patterns through the differential survival of mass extinction resistant species.
  • ...
  • It can often lead to evolutionary radiation of mass extinction surviving taxons in the mass extinction post-extinction recovery phase.
  • It can often create mass extinction evolutionary opportunity through the mass extinction vacated niche mechanism after the mass extinction event.
  • It can often establish new mass extinction evolutionary selection regimes that favor different mass extinction adaptive traits than those prevalent before the mass extinction event.
  • It can often be identified in the geological record through distinct mass extinction fossil boundary layers showing abrupt changes in mass extinction fossil diversity.
  • It can often trigger cascading mass extinction ecosystem collapse as keystone species are eliminated and mass extinction ecosystem dependency relationships are severed.
  • ...
  • It can range from being a Past Mass Extinction Event to being a Future Mass Extinction Event, depending on its mass extinction temporal occurrence.
  • It can range from being a Proven Mass Extinction Event to being a Predicted Mass Extinction Event, depending on its mass extinction evidential support.
  • It can range from being a Rapid Mass Extinction Event to being a Prolonged Mass Extinction Event, depending on its mass extinction temporal duration.
  • It can range from being a Regional Mass Extinction Event to being a Global Mass Extinction Event, depending on its mass extinction geographical scope.
  • It can range from being a Selective Mass Extinction Event to being a Comprehensive Mass Extinction Event, depending on its mass extinction taxonomic breadth.
  • ...
  • It can interact with Evolutionary Choke Point dynamics to determine which mass extinction evolutionary lineages survive through the mass extinction bottleneck.
  • It can establish mass extinction post-extinction evolutionary trajectory through the mass extinction selective survival of certain mass extinction pre-extinction species.
  • It can influence the planetary biodiversity recovery rate through its mass extinction severity and mass extinction ecosystem disruption level.
  • It can alter the mass extinction evolutionary trajectory of life on Earth by eliminating previously dominant mass extinction species groups and allowing the rise of new mass extinction evolutionary lineages.
  • It can serve as a natural mass extinction experiment demonstrating the resilience and adaptability of different mass extinction species types under extreme mass extinction environmental stress.
  • ...
• Examples:
  • Mass Extinction Event Time Periods, such as:
    • Ancient Mass Extinction Events, such as:
      • Great Oxygenation Period Mass Extinction Event (~2.4 BYA), which functioned as an evolutionary choke point for mass extinction anaerobic organisms and created mass extinction evolutionary opportunity for mass extinction aerobic life forms.
      • Cambrian-Ordovician Mass Extinction Event (~488 Mya), one of the earliest known mass extinction events affecting early mass extinction marine life.
    • Paleozoic Mass Extinction Events, such as:
      • Ordovician-Silurian Mass Extinction Event (~443 Mya), where almost 60% of mass extinction marine life was wiped out, creating an evolutionary choke point for many mass extinction marine taxons.
      • Late Devonian Mass Extinction Event (~359 Mya), which primarily affected mass extinction marine life and resulted in a significant loss of mass extinction coral reef systems.
      • Hangenberg Mass Extinction Event (~358 Mya), a late Devonian mass extinction event that caused widespread losses among mass extinction fish and mass extinction trilobites.
      • Permian-Triassic Mass Extinction Event (~252 Ma), which eradicated ~96% of all mass extinction marine species and ~70% of mass extinction terrestrial vertebrate species, representing the most severe evolutionary choke point in phanerozoic history.
    • Mesozoic Mass Extinction Events, such as:
      • Triassic-Jurassic Mass Extinction Event (~182 Mya), that led to the dominance of the mass extinction dinosaurs in the Jurassic period, demonstrating how mass extinction events can create mass extinction evolutionary opportunity.
      • Cretaceous-Paleogene Mass Extinction Event (~66 Mya), which led to the extinction of Non-Avian Dinosaurs and created an evolutionary choke point that enabled the subsequent mass extinction mammalian radiation.
      • Asteroid Impact Mass Extinction Event (~66 Mya), known as the Chicxulub impact, widely believed to have caused the Cretaceous-Paleogene Mass Extinction Event through mass extinction impact winter and mass extinction atmospheric alteration.
    • Cenozoic Mass Extinction Events, such as:
      • Eocene-Oligocene Mass Extinction Event (~34 Mya), which was associated with significant mass extinction climate changes and resulted in the loss of many mass extinction marine and mass extinction terrestrial species.
      • Holocene Mass Extinction Event (present), which is currently ongoing and driven by mass extinction human activities such as mass extinction habitat destruction, mass extinction climate change, and mass extinction pollution.
  • Mass Extinction Event Causal Types, such as:
    • Asteroid Impact Mass Extinction Events, which trigger rapid mass extinction global cooling through mass extinction atmospheric dust.
    • Volcanic Mass Extinction Events, which cause mass extinction climate alteration through mass extinction greenhouse gas emissions.
    • Climate Change Mass Extinction Events, resulting from mass extinction temperature shifts beyond mass extinction species tolerance ranges.
    • Sea Level Change Mass Extinction Events, which eliminate mass extinction coastal habitats through mass extinction flooding or mass extinction habitat exposure.
    • Anoxic Mass Extinction Events, characterized by mass extinction ocean oxygen depletion leading to mass extinction marine life collapse.
  • Mass Extinction Event Ecological Patterns, such as:
    • Marine Mass Extinction Events, primarily affecting mass extinction ocean ecosystems through mass extinction marine habitat destruction.
    • Terrestrial Mass Extinction Events, primarily affecting mass extinction land ecosystems through mass extinction terrestrial habitat alteration.
    • Selective Mass Extinction Events, disproportionately affecting specific mass extinction taxonomic groups based on their mass extinction vulnerability factors.
    • Cascading Mass Extinction Events, where initial mass extinction species loss triggers mass extinction ecological chain reactions affecting dependent mass extinction species.
  • ...
• Counter-Examples:
  • Minor Extinction Events, which affect a limited range of taxonomic groups without creating significant evolutionary choke points or reshaping global biodiversity patterns.
  • Background Extinction, which is measured by a Background Extinction Rate and represents normal species turnover rather than episodic mass extinction biodiversity collapse.
  • Life Explosion Events, such as the Cambrian Explosion, which represent rapid biodiversity increases rather than mass extinction biodiversity losses through evolutionary radiation.
  • Evolutionary Radiation Events, which involve the expansion rather than constraint of evolutionary options after passing through an evolutionary choke point.
  • Gradual Environmental Changes, which allow sufficient time for species adaptation without creating mass extinction conditions and do not function as evolutionary choke points.
• See: Mass Extinction, Evolutionary Choke Point, Cretaceous-Paleogene Mass Extinction Event, Permian-Triassic Mass Extinction Event, Ordovician-Silurian Mass Extinction Event, Climate Change, Biodiversity, Geological Period, Speciation, Biomass (Ecology), Microbial, Biosphere, Fossil Record, Alpha Taxonomy, Family (Biology), Invertebrate, Vertebrate, Evolutionary Bottleneck, Natural Selection.

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References

2014

• (Wikipedia, 2014) ⇒ http://en.wikipedia.org/wiki/extinction_event Retrieved:2014-9-20.
  • An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the amount of life on Earth. Such an event is identified by a sharp change in the diversity and abundance of macroscopic life. It occurs when the rate of extinction increases with respect to the rate of speciation. Because the majority of diversity and biomass on Earth is microbial, and thus difficult to measure, recorded extinction events affect the easily observed, biologically complex component of the biosphere rather than the total diversity and abundance of life. Over 98% of documented species are now extinct, but extinction occurs at an uneven rate. Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine invertebrates and vertebrates every million years. Marine fossils are mostly used to measure extinction rates because of their superior fossil record and stratigraphic range compared to land organisms. Since life began on Earth, several major mass extinctions have significantly exceeded the background extinction rate. The most recent, the Cretaceous–Paleogene extinction event, which occurred approximately million years ago (Ma), was a large-scale mass extinction of animal and plant species in a geologically short period of time. In the past 540 million years there have been five major events when over 50% of animal species died. Mass extinctions seem to be a Phanerozoic phenomenon, with extinction rates low before large complex organisms arose.

    Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from the threshold chosen for describing an extinction event as "major", and the data chosen to measure past diversity.

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