What new scary dinosaur will we see in Jurassic park 4 and what cast will return?

First off let me say I am totally thrilled to see a new Jurassic park film hit theaters next year. But I'm curious to which actors will comeback or will we see an entirely new different cast? Will Jeff Golblum,Sam Neil,Laura Dern,Richard Attenborough- I think he said he's done unfortunate too old maybe?,William H. Macy,Tea Leoni,Samuel L. Jackson,guy who plays Dodson,etc. but paleontologist Jack Horner said “I can't actually tell you who that will be,but you'll want to keep the lights on after seeing this. Who could Horner actually be talking about? Does this hint give us a good idea we will finally see a new Dino in the water this time? A marine reptile I should say. Dinosaurs don't swim. Could it the the ferocious king of the sea in the Jurassic period the Liopueridon? Or the Kronosaurus? Or the largest carnivore ever to roam the oceans the lethal monstrous Megladon!!!!!???? Megladon out of all of my suggestions could probably eat the T-Rex or Spinosaurus for lunch if they stepped foot in the water. They say the new Dino will be terrifying. Universal is well known for its classic horror monsters so imagine if universal can come up with their own creation of a Megalodon? 60 feet they say they can grow too. Idk about 100 ft but that's also what I've heard. Jaws has succeeded by universal so why not focus more ok the water this time? Idk give me ur take on this.

Apparently Jurassic Park 4 has been postponed so who knows what will happen when. I remember reading somewhere that new evidence suggests raptors had feathers, think about that