Biotic selectivity during the K/T and Late Ordovician extinction events

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Date of Original Version



The differing environmental effects of a glaciation and an impact event are reflected in significantly differing ecologic responses during the Late Ordovician and Cretaceous/Tertiary (K/T) mass extinctions. During the Late Ordovician glaciation most biotic changes were associated with an intensifying climatic gradient and glacioeustatic sea-level changes. During the K/T event most biotic changes were related to a short-term loss of primary productivity, consistent with a loss of sunlight and other ancillary effects of an impact. Animals in food chains that required a supply of food derived from photosynthesis suffered the greatest extinction during the K/T event. Many K/T survivors may have been buffered from the loss of primary productivity by feeding on detritus or being starvation resistant. The marked differences in ecological patterns between the two events affirms a fundamental difference in the mechanisms of extinction.

Publication Title, e.g., Journal

Special Paper of the Geological Society of America