The earliest fossil sheds light on the evolution of vermileonid flies

Abstract Vermileonidae (wormlions), a lineage close to the root of Brachycera, have long been obscured by limited fossil evidence and unresolved genus-level relationships. A new genus and species, †Crevermileo cnuae gen. et sp. nov., is described as the first Mesozoic vermileonid fossil from mid-Cretaceous Kachin amber, predating the previously oldest Eocene record. Phylogenetic analyses position this taxon close to the root of vermileonid flies. Ancestral state reconstructions of mouthparts, conducted within a tip-dated phylogenetic framework, reveal a significant shift of feeding habits during the Late Mesozoic gymnosperm-angiosperm transition. Derived vermileonids exhibit elongated mouthparts with a convex clypeus, a morphological innovation temporally correlated with angiosperm radiation. By integrating paleontological data with lineage diversification patterns of contemporary flora, our results demonstrate that vermileonid diversification occurred in 2 phases: an initial gymnosperm-associated radiation predating the Cretaceous Terrestrial Revolution (∼100 Ma), followed by angiosperm-driven diversification of derived lineages. This fossil bridges molecular divergence estimates with morphological and ecological evidence, resolving long-standing ambiguities in the family’s evolutionary trajectory.