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A phylogenetic hypothesis for ichthyopterygians is proposed, based on a cladistic analysis of 105 discrete osteological characters coded for 27 ingroup and five outgroup taxa. The monophyly of Ichthyopterygia is established; at least nine characters support its basal node. The group contains two basal species and a clade formed by the Ichthyosauria and Grippidia. All ichthyosaurs from post-Triassic strata form an unnamed clade, which in turn forms the group Euichthyosauria (new taxon) with four Late Triassic genera. The traditional Shastasauridae is poly-phyletic, with Cymbospondylus forming the sistergroup of a clade containing mixosaurs, shastasaurs, and euichthyo-saurs. In addition, Californosaurus and Toretocnemus are not shastasaurs but euichthyosaurs. Two new generic names, Macgowania and Isfjordosaurus, are proposed.