Figure 3.
Diversity of taxa (“forms,” in the literature, which are roughly equivalent to form species) of stromatolites through time. This graph plots the number of forms per 50-million-year interval and is redrawn from Fig. 2 in Awramik and Sprinkle (1999) using the same dataset. The high diversity of stromatolites during the Mesoproterozoic, 1600 to 1000 Ma, is remarkable.