There isn't a Megalodon in Jurassic.
It's a Mosasaurus.
I put that one in the #1 spot because Mosasaurus had a second set of teeth in the roof of its mouth that could slide back and forth to grind up large prey.
So if you got eaten by a Mosasaurus, you wouldn't get swallowed like Jonah or something - you'd be shredded to death.