Everything i suggest will have how i believe you could make it.

Indominus rex: So for this you would only have to re-texture the tearex and add something to the AI that if it is near a group of voxels (not sure how to spell that.) it may have a chance to change colour.

Giga: Same AI as tearex just different body.

Raptor: Smaller rex body same AI but it can jump every so often, And a few very small changes to the body.

Stego: Make the AI wander around and if you attack it it goes aggressive.

Trike: Make the AI wander around and if you attack it it goes aggressive.

Compy: the Ai will detect if its alone it will run but if its in a group of 5 then it will attack.

brachiesourus (again no clue how to spell this) doesn't move unless you shoot it then it will swing its tail and slowly spin if attacked.

Carnotourus: Same AI as tearex just different body

Now these are my ideas that i don't feel need to be prioritised,
Adding bones into the meat of the bodies.

Adding a better AI so they will duck under obsticals (can't spell) and walk over rocks something more natural. As well say two tearex meet they wont focus on the player and will instead attack each other.

Better health, especially with the indominus they need to have a good set of hide because the walk through a wall and die is pretty pathetic, perhaps the body is impenetrable except for the underbelly and the flesh, and the eyes and mouth.

Food, i wood LOVE to see a mechanic where they will become weaker and will slowly start to die unless they eat like a dead or a defeated animal, or you. Perhaps the hungrier they get the more ferocious and reckless they become compies will attack you with or without groups, tearex's will charge at you maybe hitting walls, This i would LOVE to see.

The final thing i would love is their eyes, perhaps a way to know how hungry they are and if they see you... Their eyes could be scurrying around during a hunt, or be smaller or bigger depending on how hungry they are This i would KILL for to have this it would be SO cool to see it in action!