Fig. 2. ‘Pristine’ landscape (scenario A).

Simulated tetrapod diversity patterns over time compared against the raw fossil record. Simulations were performed on a ‘pristine’ landscape with no habitat fragmentation (that is, the CRC was absent). Three metrics of biodiversity (alpha, beta and gamma diversity; Table 1) are shown for both amphibians and amniotes from Bashkirian to Kungurian from empirical data (solid black lines) and from simulated communities (dashed lines). The shaded area surrounding the dashed lines represents the variation in the 5 best-fitting simulations from a total of 25. The dashed vertical line indicates the timing of the CRC. Interval abbreviations are as in Fig. 1.