New Cretaceous snakeflies highlight the morphological disparity of Mesoraphidiidae and its response to the Cretaceous Terrestrial Revolution

Mesoraphidiidae is an extinct family of the order Raphidioptera with an evolutionary history that is largely unexplored. Here, we uncovered the evolutionary history of Mesoraphidiidae using phylogenetic comparative approaches, based on an updated morphological dataset, with an additional description of two new genera and species with distinct cephalic elongation, Dracoraphidia brachystigma gen. et sp. nov. and Teratocephala macrostigma gen. et sp. nov., from mid-Cretaceous Myanmar amber. Phylogenetic analysis shows their affinity to the subfamily Alloraphidiinae. Our results show that the radiation of species diversity and morphological disparity of Mesoraphidiidae dates back to the Lower Cretaceous and experienced a distinct peak approximately 130–118 million years ago (Ma). This timeframe aligns with the Cretaceous Terrestrial Revolution (KTR), a period from 125 to 80 Ma marked by the proliferation of flowering plants and their interactions with insects. The habitat preference of mesoraphidiid larvae to gymnosperm plants might have led to their extinction during the KTR, with the associated decline of gymnosperm diversity. Despite reduction in the occupation of morphospace by Mesoraphidiinae, there is surprising expansion of morphospace occupation by Alloraphidiinae in the Upper Cretaceous, possibly related to cephalic elongation, which may have enhanced pollen-feeding or predation ability, in response to extrinsic changes to biodiversity and ecosystems during the KTR. This study enriches our understanding of the macroevolution of snakeflies during the Mesozoic and provides new evidence for the impact of the KTR on insects.