Aigialosaurus

Aigialosaurus is a genus of Late Cretaceous marine or semiaquatic lizard classified as part of the family Aigialosauridae within the Mosasauroidea. Exclusively found in deposits of Cenomanian age near Hvar, Croatia, the genus contain one valid species, A. dalmaticus.[1] According to recent molecular and morphological data, Aigialosaurus is the oldest known member of the lineage leading to large Cretaceous marine reptiles called mosasaurs, a group most closely related to snakes among living squamates.[2][3]

Another primitive Mosasauroid, Opetiosaurus, was suggested to represent a second species of Aigialosaurus in 2009, "Aigialosaurus bucchichi",[4] though this conclusion has not been supported by recent analyses.[1]