Kronosaurus

Kronosaurus was a Pliosaur that lived in the Early Cretaceous of Australia. It was among the largest pliosaurs, and is appropriately named after the leader of the Greek Titans, Cronus. It had an elongated head, a short neck, a stiff body propelled by four flippers, and a relatively short tail. Current estimates put Kronosaurus at around 9–10 meters (30–33 feet) in length.

More real-life information: .

Jurassic Park Franchise
Kronosaurus never appeared in any films or novels. It did appear in some video games.

Jurassic Park III: Park Builder
It appears as No.118 of the Carnivore Threes in Jurassic Park III: Park Builder.

Jurassic Park: Builder
Kronosaurus appears in the underwater park update for the game Jurassic Park: Builder. It's the third aquatic creature in the park.