The early Eocene great lakes of the Green River system preserved a rich fauna, allowing detailed study of the paleoecology of the area. Two genera, †Priscacara and †Mioplosus, are interesting because they are among the earliest well-known representatives of Percoidei sensu lato, and so offer a chance to explore the evolution of the North American fish fauna. A phylogenetic analysis including †Priscacara, †Mioplosus, and representatives of some ‘basal’ percoid families suggests that †Priscacara is a member of Moronidae, and that †Mioplosus has affinities with Lateolabrax, Siniperca, and Lates. †Priscacara is recovered as paraphyletic relative to the rest of Moronidae, primarily on the basis of meristic characters; in the absence of more robust evidence, both †P. serrata and †P. liops are retained within †Priscacara. The phylogenetic position of †Priscacara suggests a trans-Atlantic connection, because Moronidae contain genera from eastern North America and Europe. †Mioplosus is suggestive of an Asian link to the Eocene Green River system, due to its relationship with the Western Pacific Lateolabrax, the Asian Siniperca, and the African/Asian Lates.