The Stratigraphy of Mass Extinctions and Recoveries

Abstract

Interpretations of the tempo of mass extinctions and recoveries often rely on the distribution of fossils in a stratigraphic column. These interpretations are generally compromised when they are not based on a knowledge of marine ecological gradients and sequence-stratigraphic architecture. Crucially, last and first occurrences of species do not record times of extinction and origination. A face-value interpretation of the stratigraphic record leads to incorrect inferences of pulsed extinction, underestimates of the duration of mass extinction, and overestimates of local recovery times. An understanding of the processes of extinction and recovery is substantially improved by knowledge of the distribution of species along marine environmental gradients, interpreting sequence-stratigraphic architecture to show how those gradients are sampled through time, and sampling along regional transects along depositional dip. Doing so suggests that most ancient mass extinctions were substantially longer and local recoveries substantially shorter than generally thought. The concepts that let geologists find petroleum allow paleontologists to reinterpret ancient mass extinctions and their recoveries. Most ancient mass extinctions were longer than the fossil record suggests, lasting hundreds of thousands of years to a few million years. Ancient recoveries from mass extinctions were shorter than thought and likely overlapped with extinction during a period of turnover.