Theory and classification of mass extinction causation

Area of Science:

• Paleontology
• Geology
• Climate Science

Background:

• Mass extinction theories require systematization, distinguishing between ultimate triggers and proximate causes.
• Ultimate causes include bolide impacts, large igneous province (LIP) eruptions, and bioevolutionary events.
• Proximate mechanisms primarily involve carbon-release (warming, acidification) or carbon-burial (cooling, increased productivity) processes.

Purpose of the Study:

• To systematize the theory of mass extinction causation.
• To classify mass extinctions using a matrix of ultimate and proximate factors.
• To critically evaluate hypotheses of common triggers for the Phanerozoic Big Five mass extinctions.

Main Methods:

• Analyzing evidence for ultimate causes: bolide impacts, LIP eruptions, bioevolutionary events, and tectono-oceanic changes.
• Investigating proximate mechanisms: carbon-release vs. carbon-burial processes and their associated environmental changes (climate, ocean chemistry, productivity).
• Classifying the Big Five mass extinctions based on their identified ultimate and proximate factors.

Main Results:

• The end-Cretaceous extinction was a bolide-triggered carbon-release event.
• The end-Permian and end-Triassic extinctions were LIP-triggered carbon-release events.
• The Late Ordovician and Late Devonian extinctions were bioevolution-triggered carbon-burial events, inconsistent with impact or LIP hypotheses.

Conclusions:

• Hypotheses of a single ultimate cause for all Big Five mass extinctions are questionable due to differing environmental and biotic patterns.
• Bioevolutionary triggers can lead to varied carbon-cycle changes, including burial or release.
• Claims of mass extinction periodicity are undermined by the disproven idea of a common extrinsic trigger.