Since the start of the Mesozoic era, several clans of (none of which, were dinosaurs), colonized the seas with various levels of success. Marine crocodiles and sea turtles are the only ones who have even remotely made it to our day (the crocodiles are represented by a single ocean-going species - the modern saltwater crocodile of the Indo-Pacific region), however. Both of these groups of reptiles were shown in the last episode of Sea Monsters, as sleek fish-hunting predators and bulkier, gentler giants of the Mesozoic seas, respectively.