THE SURPRISINGLY MODERN ROLES OF INSECTS IN TWO MID MESOZOIC ECOSYSTEMS OF NORTHEASTERN CHINA

The Early Cretaceous Yixian and Middle Jurassic Jiulongshan Formations of Northeastern China have yielded well-preserved feathered dinosaurs, pterosaurs, mammals and birds. However, it is among the insects, represented by the vast collection at Capital Normal University that the greatest amount of autecologic data has been generated, revealing associations of insects with coexisting plants, vertebrates and other insects. We present five categories of interspecific and intraspecific interactions representing six insect orders. (1) The long-proboscid pollination mode, a pollinator mutualism independently arrived at by Diptera (flies), Mecoptera (scorpionflies), Neuroptera (lacewings) and probably Lepidoptera (moths) that evolved convergent siphonate mouthparts. Mouthparts of these major insect lineages represent a broad mosaic of proboscis lengths and aspect ratios, terminal sponging structures, associated palp modifications and sucking pumps involved in imbibition of pollination drops from tubules or channels of gymnosperm ovulate organs, resulting in pollination. (2) Mimesis or camouflage was an association in which two lacewings imitated a co-occurring pinnate gymnosperm pinnule; similarly, a scorpionfly mimicked in facsimile fashion an entire co-occurring ginkgo leaf, presumably providing protection alike to both plant model and insect mimic. (3) An insect‒vertebrate association consisting of a basal lineage of Siphonaptera (fleas) possessed mouthparts of long, robust, outwardly serrated stylets for piercing thick vertebrate integument and imbibing the blood of hosts, possibly feathered dinosaurs, pterosaurs and mammals. (4) Intraspecific interactions of insects include a pair of copulating Hemiptera (froghoppers), hitherto the earliest record of copulating insects. (5) Equally spectacular are two genera of Mecoptera with exaggerated male organs, likely representing the earliest example of long-term male‒male competition in insects. These five mid-Mesozoic associations provide an augmented understanding of the role that insect speciosity had on a variety intimate and intricate ecologic relationships between insects and other contemporaneous associates of mid-Mesozoic ecosystems as well as intraspecific, evolutionary changes.