Suggestions by @josephmcnulty

Gwangi

as Harryhausen DLC in Zoo Tycoon

Ornithomimus (The Valley of Gwangi)

as Harryhausen DLC in Zoo Tycoon

Eohippus (The Valley of Gwangi)

as Harryhausen DLC in Zoo Tycoon

Styracosaurus (The Valley of Gwangi)

as Harryhausen DLC in Zoo Tycoon

Mooncalf

as Harryhausen DLC in Zoo Tycoon

Mighty Joe Young (1949)

as Harryhausen DLC in Zoo Tycoon

Rhedosaurus

as Harryhausen DLC in Zoo Tycoon

Roc

as Cryptid DLC in Zoo Tycoon

Xiphactinus

as Extinct Marine Mania DLC in Zoo Tycoon

Livyatan

as Extinct Marine Mania DLC in Zoo Tycoon

Archelon

as Extinct Marine Mania DLC in Zoo Tycoon

Ammonite

as Extinct Marine Mania DLC in Zoo Tycoon

Boar-wolf

as Star Wars DLC in Zoo Tycoon

gorax

as Star Wars DLC in Zoo Tycoon

Exogorth

as Star Wars DLC in Zoo Tycoon

Knobby white spider

as Star Wars DLC in Zoo Tycoon

Colo claw fish

as Star Wars DLC in Zoo Tycoon

Opee Sea Killer

as Star Wars DLC in Zoo Tycoon

Sando Aqua Monster

as Star Wars DLC in Zoo Tycoon

gorax

as Featured Creatures in Star Wars: Episode VI - Return of the Jedi (1956)