Mass Extinctions and Recovery
Mass extinctions are brief intervals of catastrophic biodiversity loss that repeatedly reshaped life on Earth, each followed by distinctive ecological recovery.
Definition
A mass extinction is a geologically rapid loss of a large fraction of the world's species across many groups, and recovery is the subsequent rebuilding of biodiversity and ecosystems.
Scope
This topic covers the major mass extinction events, especially the big five, their proposed causes such as bolide impact and large igneous province volcanism, the patterns of selectivity in who survives, and the dynamics of recovery and rediversification afterward.
Core questions
- What defines a mass extinction relative to background extinction?
- What caused the major extinction events?
- Which groups and traits survive mass extinctions?
- How long and by what patterns do biotas recover?
Key concepts
- Background versus mass extinction
- Impact and volcanic triggers
- Extinction selectivity
- Recovery and rediversification
Key theories
- Impact hypothesis for the end-Cretaceous extinction
- An iridium anomaly and other evidence support a large asteroid impact as the trigger of the end-Cretaceous mass extinction that ended the non-avian dinosaurs.
- Mass extinction as a distinct regime
- Quantitative analysis shows mass extinctions stand out from background extinction, sometimes favoring different traits and reshaping evolutionary trajectories.
Clinical relevance
The study of past mass extinctions provides essential perspective on rates, causes, and consequences of biodiversity loss, informing assessment of the current biodiversity crisis and ecosystem resilience to rapid environmental change.
History
The 1980 Alvarez hypothesis of an asteroid impact at the Cretaceous-Paleogene boundary, supported by the later identification of the Chicxulub crater, revolutionized extinction studies. The Raup and Sepkoski analyses then established mass extinctions as a quantifiable feature of the record.
Debates
- Impact versus volcanism in major extinctions
- The relative roles of bolide impact and large igneous province volcanism in driving mass extinctions, especially the end-Cretaceous and end-Permian events, remain debated.
Key figures
- Luis Alvarez
- Walter Alvarez
- Paul B. Wignall
- Anthony Hallam
Related topics
Seminal works
- alvarez1980
- raup1982
Frequently asked questions
- What is the difference between mass and background extinction?
- Background extinction is the ongoing low-level loss of species, while a mass extinction is a brief event in which a large fraction of species across many groups die out.
- What caused the dinosaurs' extinction?
- The leading explanation is a large asteroid impact at the end of the Cretaceous, supported by an iridium anomaly and the Chicxulub crater, possibly with volcanism.