Mosasaurs
The dominant sharp toothed reptilian of the water. A superior to the other known marine reptiles (the icthyrosaurs, plesiosaurs, and pliosaurs). The mosasaurs made the icthyrosaurs go extinct from out competing them for food and reduced the numbers of the plesiosaurs and the pliosaurs. They breathed air, gave birth to live young, and grew very large, largest being 57 feet long, and had scales as well. The paddles/fins they had were webbed from their long digit bones and their tails were shaped like a sharks, they had a double hinged jaw like a snake and very sharp set of teeth like a crocodiles and was used to crush the shell and swallowed the animal whole just like a snake. The mosasaur ate other fish, mollusks, and sometimes sea turtles if the mosasaur was big enough.