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Mass extinctions in the marine fossil record
Science (New York, N.Y.)
|March 19, 1982
Summary
Four distinct mass extinctions in marine life occurred during the Ordovician, Permian, Triassic, and Cretaceous periods. Fossil data analysis reveals these events significantly exceeded background extinction rates over geological time.
Area of Science:
- Paleontology
- Marine Biology
- Evolutionary Biology
Background:
- Mass extinctions represent significant disruptions to marine ecosystems.
- Understanding extinction patterns is crucial for comprehending evolutionary history.
- Previous studies have identified numerous extinction events throughout Earth's history.
Purpose of the Study:
- To statistically differentiate major marine extinction events from background extinction rates.
- To analyze trends in background extinction rates over geological time.
Main Methods:
- Compilation and statistical analysis of fossil data for invertebrate and vertebrate families.
- Comparison of extinction event magnitudes against background extinction levels.
Main Results:
- Four statistically distinct mass extinctions were identified in the marine realm: late Ordovician, Permian, Triassic, and Cretaceous.
- A Devonian extinction event was noted but did not reach statistical significance in this dataset.
- Background extinction rates show a declining trend since the Cambrian period.
Conclusions:
- The identified four events represent major evolutionary turning points in marine life.
- The decline in background extinction rates supports the hypothesis of increasing fitness optimization through evolutionary time.
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