Plesiosauria Plesiosauria The Plesiosauria (; Greek: πλησίος, "plesios", meaning "near to" and "sauros", meaning "lizard") or plesiosaurs are an order or clade of Mesozoic marine reptiles (marine Sauropsida), belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period, possibly in the Rhaetian stage, about 203 million years ago. They became especially common during the Jurassic Period, thriving until their disappearance due to the Cretaceous–Paleogene extinction event at the end of the Cretaceous Period, about 66 million years ago. They had a worldwide oceanic distribution. Plesiosaurs were among the first fossil reptiles discovered. In the beginning of the nineteenth century,
T-Rex: Back to the Cretaceous continued for two weeks on location in Dinosaur Provincial Park. Yet the filmmakers faced a challenge in finding a realistic environment to set the live-action filming portion for the Cretaceous period sequences when Ally finds herself wandering amidst the lush vegetation of 66 million years ago. The location used to film Cretaceous period scenes in the end was in the Olympia rain forest in upper Washington state. The special considerations that must be made when working with IMAX 3D presentation also made it crucial that the background features of the shooting locations were ideal. Besides shooting locations, extensive computer-generated imagery