Kronosaurus

                                

Now is Kronosaurus.  He is not a real dinosaur.  Dinosaurs were all land creatures but Kronosaurus lived in water.  He is like a crocodile with flippers instead of legs.  He also had powerful crocodile-like jaws.  His bones were found in Australia and Colombia.  He was 30 feet long and weighed 22 tons.  He is a pliosauroid.
This video shows a Liopleurodon, which was another pliosauriod that was very similar to Kronosaurus and was about the same size.