Figure 3.

Logarithmic plots (both scales logarithmic) of the distribution of the number of genera in a family, assuming background and cataclysmic extinctions. The three panels (from left to right) correspond to τ = 2,4 and 10. In all cases λ = 1; γ = 0.1; n₀ = 1. For the sake of display the points of the probability mass function have been joined by lines:- solid (μ = 1); dotted (μ = 1.5) and dot-dash (μ = 0.5).