Figure 4.

Survivorship of Paleozoic orders after mass extinctions is unrelated to the size of the extinction bottleneck. (A) The frequency distribution of genera surviving a mass extinction does not differ significantly for DCW orders (which became extinct by the end of the stage immediately following a mass extinction) and the other well preserved, contemporaneous orders. (B) The geologic durations of Paleozoic orders following the end-Ordovician, late Devonian, and end-Permian extinctions are unrelated to the number of genera within those orders that survived those events. Total number of orders = 138; total number of order × mass extinction encounters = 242; only Paleozoic orders were analyzed because postPaleozoic extinction lack ordinal DCWs, and extant orders dominate the postPaleozoic dataset, undermining comparisons of postextinction durations. When no genera within an order were recorded crossing a given extinction event, genealogical continuity was assumed, and a value of one surviving genus was assigned.