The Yanliao entomofauna, first established by Hong in 1983, refers to a Middle Jurassic insect assemblage widely distributed in northern China. The fossil insects are primarily preserved in the Haifanggou Formation and its correlated strata. In the beginning of this century, the Yanliao entomofauna was revived thanks to the discovery of abundant exceptionally preserved fossils, especially a huge number of insects, in the Daohugou area. Then, the Yanliao biota became well-known, and subsequently enlarged with more fossils collected from the interbeds of the overlying Tiaojishan Formation. Recently, the Yanliao biota has been divided into an early assemblage, represented by the Daohugou beds (Middle Jurassic to earliest Late Jurassic), and a late assemblage, represented by the Linglongta beds (early to middle Late Jurassic). The early insect assemblage, i.e. fossil insects from Daohugou, contains at least 24 insect orders, representing one of the most diverse entomofaunas in geological history. The age difference between core fossil layers of the Daohugou assemblage and the Linglongta assemblage is less than 5 Ma, but no same animal species from both have been discovered to date, because of violent tectonic movements and fierce volcanic eruptions. The representative insect from the early assemblage is Yanliaocorixa chinensis, which is distinctly different from the dominated corixids from the late assemblage. Insects of Yanliao entomofauna generally resemble those from the Shar Teg biota from Mongolia and the Karatau biota from Kazakhstan. The Yanliao biota rapidly declined in middle of the Late Jurassic (ca. 155 Ma) with the advent of arid climate, whereas some of the relict groups migrated southwards. Until the mid-Cretaceous, represented by the Burmese amber, a number of endemic insect groups of Daohugou are still recorded, but they have never been found in the Jehol biota, representing relicts of the Yanliao entomofauna.
Supercritical fluids as recorded in quartz megacrysts of the Late Jurassic porphyritic granitic dyke in the giant Dongping gold deposit, Northern China
