Fig. 4 in The fossil record of early tetrapods: Worker effort and the end-Permian mass extinction

Fig. 4. Cumulative discovery curves of species of early tetrapods showing the relative completeness for each of the nine major geographic regions: North America, Europe, and Africa (A), South America, Greenland, and Australia (B), Asia, India, and Russia (C), 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. Total numbers of taxa are given for each continent.