Chaohusaurus geishanensis (Young and Dong, 1972, Early Triassic, IVPP V 4001, AGM CHS-5, 180cm in length) is one of the smallest ichthyosaurs known. It is transitional between the primitive Grippia and the derived Parvinatator. The radiation of the basal ichthyosaurs must have been very rapid or somewhere preceded the Triassic.
The enormous eyes and relatively large teeth suggest a nocturnal hunter. The neck is reduced to fewer than three vertebrae.