Diverse plant-insect associations from the latest Cretaceous and early Paleocene of Patagonia, Argentina

Abstract

Little is known about the recovery of terrestrial ecosystems after the end-Cretaceous extinction outside of the Western Interiorof North America, relatively close to the 66 Ma bolide impact crater in Chicxulub, Mexico. A previous report showed that in Patagonia, Argentina,insect damage on fossil leaves decreased from the latest Cretaceous to early Paleocene but recovered to pre-extinction levelswithin ca. four million years. Here, we present the first detailed study of these Patagonian plant-insect associations, key componentsof terrestrial food webs, during the latest Cretaceous and three time slices from the early Paleocene recovery. The lithologic units studiedare the uppermost Cretaceous portion of the Lefipán Formation and the Danian Salamanca and Peñas Coloradas formations in Chubut,Argentina. Seven functional feeding groups are present throughout: hole feeding, margin feeding, skeletonization, surface feeding, piercingand sucking, mining, and galling. Fifty damage types (DTs) were present at Maastrichtian localities, and 39?48 were found at Danian localities.Plant-insect associations that apparently went locally extinct at the end of the Cretaceous include several gall, mine, and piercingand-sucking DTs. Based on our preliminary leaf morphotypes, host plants did not provide refuge for specialized insect herbivores across theK/Pg boundary. Despite a decrease in insect damage diversity after the bolide impact, Danian floras hosted a rich array of DTs, including specializeddamage such as mines and galls. Many of these early Paleocene DTs were not found in the terminal Cretaceous, providing evidencefor a rapid recovery of plant-insect associations regionally.