Triassic fossils are rare but crucial for understanding the early evolution of large insect clades including beetles (Coleoptera). Their phylogenetic assignment is problematic because of fragmentary preservation, yet crucial for the correct use of the information they provide. Here an analysis is presented of the phylogenetic position of Leehermania prorova, the Late Triassic compressed fossil which was described and hitherto widely used as the oldest representative of Staphylinidae (rove beetles) in the suborder Polyphaga. By contrast with the intuitive character assessment made in the original description, a phylogenetic analysis of Leehermania is performed using an extensive morphological matrix of extant Coleoptera provided by the Beetle Tree of Life project, constrained in view of the latest relevant molecular phylogenies. As a result, Leehermania is identified as an extinct lineage within the beetle suborder Myxophaga, closest to the modern family Hydroscaphidae. Excluding Leehermania from Staphylinidae and placing it in Myxophaga amends erroneous assumptions about early diversification of rove beetles and enhances our views of the evolutionary history of Coleoptera.