Fig. 1. Family level diversity for some Paleozoic orders, reported in Labandeira and Sepkoski (1993) as the upper panel in their Fig. 2. Abbreviations: Pz, Paleozoic; Mz, Mesozoic; Cz, Cenozoic. Note end-Permian mass extinction at the Paleozoic-Mesozoic era boundary. Some orders with distinctive Paleozoic clades are indicated by a lighter shade of blue