Fig. 6 in The fossil record of early tetrapods: Worker effort and the end-Permian mass extinction

Fig. 6. Cumulative discovery curve of species of early tetrapods showing the relative completeness for each of the eight stratigraphic series, divided into two panels, from Upper Devonian to Middle Permian (A), and Upper Permian to Upper Triassic (B), plotted against decades in research time. The horizontal line marks the "half life" of the discovery curve, the date by which half the currently valid taxa had accumulated. Numbers of taxa per series are: Upper Devonian (17), Lower Carboniferous (25), Upper Carboniferous (108), Lower Permian (125), Middle Permian (36), Upper Permian (20), Lower Triassic (100), Middle Triassic (46), Upper Triassic (5), Jurassic (5), Cretaceous (1).