Fig. 1.

Maximum body size of insect assemblages, represented here by the insect silhouettes, has varied considerably through geological time. Using a modeling approach and a compilation of more than 10,500 measurements of wing size of insect fossils, the work by Clapham and Karr (9) shows that the relationship between maximum size in an assemblage and atmospheric oxygen concentration (or partial pressure) was maintained from the Mid-Carboniferous until ∼130 Mya in the Early Cretaceous. Thereafter, the relationship was decoupled by predation, initially by birds (20) and later, by birds and bats. Moreover, the work by Clapham and Karr (9) also shows that the tendency of increasing maximum insect size to the tropics (14) is a constant feature of insect assemblages through time.