Fig. 2.

(A) Time series of sampled genus diversity, number of through-ranger genera, and number of stratigraphic packages (i.e., local sections) in Laurentia from Middle Ordovician (Dapingian) through Early Silurian (Wenlockian) time. (B) Genus extinction rate (43) and package truncation rate (14) within each interval. Diversity and extinction rates are based only on the genera sampled in a given interval and exclude unobserved “through-ranger” genera. (C) Heatmap showing the importance (measured as OOB error) of each predictor in classifying genera as extinct or surviving from random forest models of each interval. Variables are ranked from top to bottom by their importance in the late Katian interval. (D) Area under receiver operating characteristic curve (AUC), a measure of model sensitivity, for each interval. Perfect classification would be indicated by an AUC of 1.0, a model that is no better than random would have an AUC of approximately 0.5. The Rhuddanian model fails to predict any extinctions and hence AUC is undefined for this interval. Dap = Dapingian, Darr = Dariwillian, San = Sandbian, K₁ = early Katian, K₂ = late Katian, H = Hirnantian, Rh = Rhuddanian, Ae = Aeronian, Tely = Telychian, Wen = Wenlockian.