The Hueneosauria contain the more derived ichthyosaurs, which have the morphology of a fish. The group originated in the early Triassic and became extinct during the Cretaceous.
References
^Maisch, M. W.; Matzke, A. T. (2000). "The Ichthyosauria". Stuttgarter Beiträge zur Naturkunde, Serie B. 298: 1–159.