ABSTRACT
In the water the dominant predators were massive marine lizards, the mosasaurs, which gradually replaced the ichthyosaurs of the Jurassic. Plesiosaurs continued to thrive, along with giant turtles, but marine crocodiles disappeared early in the Cretaceous. Fish evolved rapidly, but the more primitive holostean bony fish of the Jurassic were gradually replaced by the teleostean bony fish, and by the end of the Cretaceous most holosteans had disappeared. Early teleosts were primitive, includ - ing herring-like and salmon-like ancestors. The ancient hybodont sharks made their final appearance in the Cretaceous. Their advanced shark descendants were numerous and included many modern forms; skates and rays had also essentially reached modern conditions. Mawsonia is the last known fossil coelacanth and was thought to be the last representative of the group until the discovery in 1938 of a living representative.
