Abstract
Insects are among the most diverse and ecologically significant groups in the fossil record, providing key insights into palaeoecology and diversity evolution of terrestrial ecosystems. This study reports a new insect fossil assemblage from the Chang 6 Member of the Yanchang Formation in the Ordos Basin, Huanglong, Shaanxi Province of China. The assemblage is dominated by Hemiptera and Coleoptera, with additional taxa belonging to Blattodea, and Plecoptera. Comparative analyses of entomofaunal composition show that Mesoblattinidae and Cupedidae co-occurred in both the Huanglong and Madygen entomofaunas, whereas Zygophlebiidae and Thaumatomeropidae, characteristic taxa of Madygen, are also documented in the Tongchuan entomofauna, highlighting ecological connectivity among these insect assemblages. The occurrence of Plecoptera (stoneflies), together with lithological evidence, could have indicated stronger hydrodynamic conditions than those of the Tongchuan fauna, consistent with a palaeogeographic scenario of enhanced water mobility during the contraction phase of the Chang 6 Member lacustrine basin. Furthermore, the warm, humid climate and extensive swamp forests of the Middle–Late Triassic likely promoted cross-regional insect dispersal and radiation.
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