Moanasaurus Moanasaurus 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 paddle bones. It reached 12 m in length and the skull is 78 cm, which shows that Moanasaurus was one of the largest in the family of mosasaurinae.