Figure 6

Schematic representations of lineage evolution with varied rates of morphological change and diversity increase. The bottom graphs show the relationship between time and rates of morphological change (the dashed line) and diversity increase (the solid line). The top row of graphs shows the number of species (number of branches) present at any given time (along the y-axis) and the range of morphologies represented by those species (width along the x-axis). All three scenarios (A, B, and C) show increasing diversity over time. In case A, the rate of morphological change peaks early and then returns to an average rate (dashed line). This is reflected in the corresponding tree that has similar widths (range of morphologies present) at the bottom (early in the clade’s history) and the top (late in the clade’s history). Reproduced from Abe and Lieberman ([2012]), copyright The Paleontological Society.