Figure 1. An overview of the possible triggers of insect diversification over time.

The insect evolution was punctuated by (a) five known mass extinction events (red arrows), and has seen the (b) origin of main key innovations and the rise of major clades. Environmental changes may also be major determinants of diversity dynamics like the (c) global temperature (red curve highlighting the cooling and warming events) and as sea-level fluctuations (blue curve); as well as (d) geological events such as volcanism due to tectonic movements (CFBs, continental flood basalts; LIPs, large igneous provinces), or meteorite impacts, which modify atmosphere composition and impact diversity. Cm = Cambrian, O = Ordovician, S = Silurian, D = Devonian, C = Carboniferous, P = Permian, Tr = Triassic, J = Jurassic, K = Cretaceous, Pg = Paleogene, and N = Neogene. The pictures (fossil and tree), drawings (dragonfly, caterpillar, and plants), and graphs were taken and made by Fabien Condamine. Figure drawn with PowerPoint.