What is a liopleuradon?

a HUGE ANCIENT SCARY SUPER BIG HORRIFIC SEA MONSTER. it lived in the dinosaur times.. and its soo big and and scary omg.. i, being 5"5 would be about the size of its fin and its fin compared to its body is like a finger to an arm, man!! its craazy. they have a big loong face with looots of teeth.. (to give image.. a full grown big one is bigger then a blue whale.. blue whales are the largest animals on the planet i think..)