Archaeopristrix was the first fossil saurocete to be discovered and remains the best-preserved example of post-Cretaceous mosasaur diversity.  Known from a virtually complete skeleton, Archaeopristrix shows all the major developements that characterize today's lizardwhales, including a bent, fin-supporting tail, reduced hind flippers, and nostrils placed above the eyes.

    Outwardly, this ancient lizardwhale probably resembled the modern Nile mosasaur (genus Apep) in appearence and behavior.  One can imagine Archaeopristrix lounging around the rivers of what is now the Middle-East, waiting to snap up any unwary dinosaur that ventured too close to the water.