Kalmar "Genus Ichthyosaurus" tana nufin rukuni ko nau'in halittu masu rarrafe na ruwa waɗanda suka rayu a zamanin Mesozoic, kimanin shekaru 245 zuwa 90 da suka wuce. Sunan "Ichthyosaurus" ya fito ne daga kalmomin Helenanci "ichthys" (ma'anar kifi) da "sauros" (ma'anar lizard), kuma yana nuna kamannin kifi na waɗannan dabbobi. Ichthyosaurs sun dace sosai da salon rayuwa na ruwa, tare da sassauƙan jikin jiki, gaɓoɓi masu kama da ƙafafu, da wutsiya mai ƙarfi. Ana la'akari da su a matsayin ɗaya daga cikin ƙungiyoyi masu rarrafe na ruwa masu ban sha'awa kuma masu nasara waɗanda suka wanzu, tare da rarrabawar duniya da nau'ikan daidaita yanayin muhalli.