They're going to dress a REAL great white shark in a Mosasaur costume and release him in to the lagoon. What happens, happens.
It'll be interesting to see what they do for the effect.
The Ops team at opening:
I would say, perhaps the Mosasaurus replaces the Paras current location (by the manner of a jumping for food sort of thing), and the Para's head over to the first scene; so they can be with the Gallimus.