It is based on the Rite of Spring segment of the 1940 Disney animated feature film Fantasia.
In Disneyland, it comes immediately after the Grand Canyon between the Tomorrowland and Main Street stations. In Tokyo Disneyland, it is located in a mining shaft behind Big Thunder Mountain Railroad, heralded by a Triceratops skeleton at the entrance to the tunnel.
At the Primeval World, guests see a number of dinosaurs in a supposed natural habitat after traveling back in time. This includes a forest inhabited by Edaphosaurus, a swamp with a feeding herd of Brontosaurs and Pteranodons perched upon rocks and waterfalls, a Triceratops family and their nest, a group of Ornithomimus at a small watering hole in a scorching desert, and a Tyrannosaurus battling a Stegosaurus in a volcanic landscape. The Tokyo version merges the Pteranodon and Ornithomimus vignettes into one scene and utilizes figure molds created for the Universe of Energy to depict its brontosaur herd.
Disneyland's diorama is accompanied by the theme for the 1961 film The Mysterious Island, while Tokyo's diorama uses the original Magic Skyway soundtrack.
Dinosaurs and other Prehistoric Animals
Edaphosaurus - Actually a synapsid (a reptile-like ancestor of mammals) that died out before the dinosaurs existed, though this is a common mistake. They are among the first creatures shown, and have characteristic glowing red eyes.
Several paleontological mistakes are found in the diorama. This can be forgiven by the fact that it was created in the 1960s and was predominately rooted in an animated sequence that was created in the 1940s.
As with many dinosaur-based media in popular culture, it depicts dinosaurs from all different time periods and places in the same habitat.
Many of the dinosaurs are out of proportion to their actual size.
The Brontosaurus are seen chewing plants like cows. This is known to be incorrect, as they swallowed their food whole and it was broken down by gizzard stones (gastroliths)
Brontosaurus had spines.
Brontosaurus did not drag its tail on the ground.
Stegosaurus's tail should be more elevated and have only four spikes instead of five.
Struthiomimus had feathers.
Struthiomimus could not pronate their wrists.
Pteranodon is shown standing on its hind legs with its wings spread out like a vulture, when it should be on all fours with its wings folded like a vampire bat.
Pteranodon like all pterosaurs also had fur and lacked bat wings.
Edaphosaurus went extinct before the dinosaurs existed, and it should have naked mammal-like skin instead of scales.
The Tyrannosaurus rex near the end has a number of anatomical faults: