No post-Cretaceous ecosystem depression in European forests? Rich insect-feeding damage on diverse middle Palaeocene plants, Menat, France

摘要

Insect herbivores are considered vulnerable to extinctions of their plant hosts. Previous studies of insect-damaged fossil leaves in the US Western Interior showed major plant and insect herbivore extinction atthe Cretaceous–Palaeogene (K–T) boundary. Further, the regional plant–insect system remaineddepressed or ecologically unbalanced throughout the Palaeocene. Whereas Cretaceous floras had highplant and insect-feeding diversity, all Palaeocene assemblages to date had low richness of plants, insectfeeding or both. Here, we use leaf fossils from the middle Palaeocene Menat site, France, which hasthe oldest well-preserved leaf assemblage from the Palaeocene of Europe, to test the generality of theobserved Palaeocene US pattern. Surprisingly, Menat combines high floral diversity with high insectactivity, making it the first observation of a 'healthy' Palaeocene plant–insect system. Furthermore,rich and abundant leaf mines across plant species indicate well-developed host specialization. The diver-sity and complexity of plant–insect interactions at Menat suggest that the net effects of the K–Textinction were less at this greater distance from the Chicxulub, Mexico, impact site. Along with theavailable data from other regions, our results show that the end-Cretaceous event did not cause a uniform,long-lasting depression of global terrestrial ecosystems. Rather, it gave rise to varying regional patternsof ecological collapse and recovery that appear to have been strongly influenced by distance from theChicxulub structure.