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Pollinating insects played a decisive role in the origin and early evolution of the angiosperms. Pollinating orthorrhaphous Brachycera fossils (short-horned flies) collected from Late Jurassic rocks in Liaoning Province of northeast China provide evidence for a pre-Cretaceous origin of angiosperms. Functional morphology and comparison with modern confamilial taxa show that the orthorrhaphous Brachycera were some of the most ancient pollinators. These data thus imply that angiosperms originated during the Late Jurassic and were represented by at least two floral types.
The ancestors and time of appearance of angiosperms remain obscure (1-5). The earliest fossil evidence of nectar secretory tissue is provided by the Santonian-Campanian flowers from Sweden (6). The oldest angiosperm pollen grains have been found in Israel, in strata of Early Cretaceous time (Late Valanginian to Early Hauterivian) (7). The earliest recognized angiosperm inflorescences have been recovered from rocks of Late Hauterivian Age at Jixi, China (8).
The origin and early evolution of flowering plants are probably related to the coevolution of insect pollinators (9- 1). Cretaceous and Tertiary flower-visiting insects were diverse and include an impressive variety of Coleoptera (beetles), Diptera (true flies), Lepidoptera (moths), Hymenoptera (wasps and bees), and other less diverse taxa, such as Thysanoptera (thrips). Some highly faithful pollinators such as butterflies and cyclorraphan flies appeared in the middle Tertiary (12). Few pre-Cretaceous pollinating insects are known. Small insects, especially flies and parasitoid wasps, may have been important then and thus in the origin and evolution of angiosperm pollination (13). Here I describe Late Jurassic pollinating orthorrhaphous Brachycera with well-preserved nectaring mouthparts.
Early pollinating insects have long tubular mouthparts designed for feeding on or extracting nectar from long tubular flowers (9-11). Other examples of Jurassic insects having this type of mouthpart include nemonychid weevils, which probably fed on bennettitaleans or cycads (14), and a monotrysian Lepidopteran with a siphonate proboscis (15, 16).
I collected the fossil Brachycera at a locality near Beipiao City, Liaoning Province, China, from nonmarine sedimentary rocks of the Yixian Formation (17). These rocks contain abdundant remains of insects (18, 19), fishes, conchostracans, reptiles, birds, and mammals of Late Jurassic (approximately Tithonian) age (20).
Extant Brachycera comprise a wide variety of flower visitors (9, 10). Most orthorrhaphous Brachycera feed on flowers as adults. The new fossil...