lation from the literature of time-estimate ranges for numerous associations provides an assessment of major patterns not only in the clustering of the timing of associations, but also for recording major gaps that would indicate significant environmental perturbation. For example, the contrast of older plant–insect associations during the earlier Pa
leogene from more recent Neogene radiations of phytophagous insects on similar herbaceous plant clades (Fig. 2.4 in Labandeira 2002a), indicates a major disruption during the mid-Cenozoic. This shift is perhaps attributable to aridification, shifting vegetation patterns, and an ensuing response by insect herbivores.