Biostratigraphic Significance of Jurassic Cicadomorphan Insects in the Yanliao Biota, China

The Yanliao Biota of northern China represents a key Middle–Late Jurassic terrestrial fossil assemblage, which can be divided into an early assemblage represented by the Daohugou beds (Middle Jurassic) and a late assemblage represented by the Linglongta beds (early to middle Late Jurassic), yielding exceptionally preserved vertebrate and invertebrate fossils, particularly diverse insects. Stratigraphic correlation of terrestrial deposits has traditionally relied on palynology, conchostracans, and bivalves, whereas insect fossils are often overlooked.Cicadomorphan insects, however, exhibit moderate dispersal ability and high diversity in the Yanliao Biota,and thus represent an important but largely untapped indicator for biostratigraphic correlation of fossiliferous terrestrial strata. Based on taxonomic work on cicadomorphan insects from the Yanliao Biota, this study applies five representative taxa to constrain stratigraphic correlations and explore palaeobiogeographic patterns across northern China and adjacent regions. (1) The most abundant froghopper taxon, Anthoscytina beipiaoensis (= A. perpetua), in the Daohugou assemblage (Inner Mongolia) is shown to be conspecific with material from the Haifanggou Formation of Beipiao (western Liaoning), indicating strong biostratigraphic equivalence between these two classic fossil localities. (2) The discovery of Jurocercopis grandis, a giant froghopper previously known only from the Daohugou beds, in the Yangshuzhuang Formation of the Jiyuan Basin (Henan), and its probable occurrence in the Yan’an Formation of the Ordos Basin (Shaanxi), extends its geographic range and demonstrates that these units are temporally comparable to the Daohugou–Haifanggou deposits. Similarly, the widespread occurrence of the froghopper Qibinius maculatus in the Daohugou beds, Yangshuzhuang and Yan’an formations provides additional biostratigraphic evidence linking these strata. (3) The identification of Kisa fasciata (Archijassidae) from both the Yangshuzhuang and Yan’an formations, with the same species also described from the Bathonian Itat Formation of Krasnoyarsk, Siberia, supports interregional stratigraphic correlation across north central China and central Siberia during the Middle Jurassic. With the uplift of the Taihang Mountains, the Jiyuan Basin was probably separated from the Ordos Basin during the deposition of the Ma’ao Formation. Shared cicadomorphan assemblages between the Jiyuan and Ordos basins during the Middle Jurassic, including dominant taxa such as K. fasciata and Q. maculatus, indicate extensive faunal exchange and suggest that these basins were interconnected during this time. (4) The occurrence of Cicadomorpha guancaishanensis (Palaeontinidae) from the Tiaojishan Formation of northeastern China (Linglongta beds), constrained by U–Pb zircon dating to ~157 Ma, shows close morphological similarity to species from the Glushkovoskaya and Ukurey formations of Transbaikalia, providing a basis to constrain these poorly dated units to the early Late Jurassic. These results provide a basis for the correlation of important fossil-bearing terrestrial stratigraphic units and offer new insights into palaeobiogeographic connections across Eurasia during the Jurassic.