Lioplurodon: -

Meaning smooth-sided teeth, this dinosaur was one marine reptile. Lived around the age near bout middle-Jurassic period, it was a predator. It belongs to Pliosauridea, a deadly carnivore which could have grown up to a length 21 feet was mainly said to reside in England and France and the younger species of the same was said to reside in Russia. It was neither the fastest swimmer nor the most powerful ocean predator but still made its way into this list because of its deadly predatorial behaviour and avenging attitude.