Pollination drops, pollen, and insect pollination of Mesozoic gymnosperms

Recent focus on plant-insect associations during the angiosperm radiation from the last 30 million years of the Early Cretaceous has inadvertently de-emphasized a similar but earlier diversification that occurred among gymnosperms. The existence of gyrn nospen n -insect associations during the preangiospernious Mesozoic is evidenced by inouthparts capable of reaching and imbibing pollination drops or similar fluids, availability of pollen types consistent with entomophily, and opportunities for related consumption of pollen, seeds, and reproductivek, associated tissues in major seed-plant groups, namely seed ferns, conifers, cycads, bennettitaleans, and unetaleans. Based on stereotypical plant damage, head-adherent pollen, gut contents, wing structure, mouthpart morphology and insect damage to plant reproductive organs, the likely nectarivores, pollinivores and pollinators were orthopterans, phasinatodeans, webspinners, sawflies and wasps, moths, beetles, inecopteroids, and true flies. These associations are ranked from possible to probable although the last three insect clades provide the strongest evidence for pollinator activity. We docurnent two mid Cretaceous examples of these associations-cycadeoideaceous bennettitaleans and beetles and a cheirolepidiaccous conifer and flies-for which there are multiple lines of evidence for insect consumption of plant reproductive tissues but also pollination mutualisins. These data hiahli2ht the independent origin of a major phase of plant-insect pollinator-related associations during the mid iVlesozoic that served as a prelude for the separate, iterative and later colonization of angiosperms.