Jit nfen g Zhang

As they had been and continued to be, insects were undoubtedly the most successful animals in the Jehol Biota. This has been confirmed by the extremely high diversity of at least 500 species referable to over 100 families within 17 orders based on over 10,000 specimens Collected from the non-marine rocks in northern Hebei and western Liaoning provinces. This extremely high diversity and superb preservation of imprints are quite rare in the geological history throughout the world. These fossil insects have provided a vivid picture of the late Mesozoic, in which some of them flew in the sky, some crawled on the ground, and some swam in the water, some fed on plant leaves, seeds or fruits, some were saprophagous, and some preyed on other insecrs or sucked blood of birds or beasts. Among these fossil insecrs, some are familiar to us, such as wasps {Order Hymenoptera), mosquitoes anil flies (Order Dipera), beetles (Order Coleoptera), cockroaches (Order Blattaria), dragonflies (Order Odonata) and grasshoppers (Order Orthoptera). These insects open a window through which we have caught a glimpse of the late Mesozoic entomofauna in East Asia. Comparing them with modern insect faunas, we also know more about insect phylogeny and evolution. Moreover, many components had special forms and ecological characteristics, which enable us to reconstruct the paleogeography, paleoclimate and paleoecology. One of the most interesting aspects is many kinds of flower-visiting insects found from this entomofauna, such as flower bugs, tumbling flower beetles, brachyceran flies, digger wasps and cockroaches. From the same locality and the same rocks, the flowering plants have also been recovered. These wonderful discoveries have provided important data in the discussion of the origin of flower-visiting insects and flowering plants as well as their revolutionary relationships.

In the Jehol Biota, certain geographically widespread and dominant insect species have been found in almost every terrestrial basins in northern Hebei and western Liaoning provinces. They usually had abundant individuals and are easy to collect, with some important and familiar representatives as follows.

Ephemeropsis trisetalh (Figs. 71, 72), a giant niavfly assigned to the family

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