Moanasaurus (From Māori moana "sea" and Greek sauros "lizard"; meaning "Sea Lizard") was a genus of mosasaur from the Late Cretaceous period. Its fossil remains have been discovered in the North Island of New Zealand. Moanasaurus was a very large mosasaurine known originally from a disarticulated skull, vertebrae, ribs and flipper bones. The skull measures 78 cm in length, which shows that Moanasaurus was one of the largest in the subfamily of Mosasaurinae. Researchers argue that some Antarctic Mosasaurus remains (including a "large, fragmentary skull") may be attributed to this genus.