Predator X has a skull estimated at 3m long. The whole animal is estimated at 15m long as Pliosaur skulls are estimated at 1/5 the animal length. However, an older estimate for Pliosaurs was that thier skulls were 1/7 the animal length. If this estimate is correct and the modern one is not. That would mean Predator X would have been 21m long. Surpassing Megalodon in length and rivaling Basilosaurus and the modern Sperm Whale as the largest predators ever to live. It is though More likely the newer estimate is the more accurate.