Young and adventurous reporter Edward Malone (Lloyd Hughes) is dispatched by his editor at the London Record Journal to cover a lecture by the boisterous Professor Challenger (Beery), who is convinced that dinosaurs are still roaming the earth. While the community thinks him a crackpot, he finds a believer in the esteemed hunter/explorer Sir John Roxton (Lewis Stone), who befriends Malone. Malone is introduced to Paula White (Bessie Love), whose father was left behind in the Amazon outback to contend with the mammoth creatures; it's the father's diary, featuring sketches of the dinosaurs, that's proof positive for Challenger of their existence. Soon a rescue mission is under way and Paula, Malone, Challenger and Roxton are awestruck by the presence of brontosaurs, pterodactyls and allosaurs right before their eyes! The turbulent assaults of these prehistoric monsters, unexpected encounters and a frenzied volcano sequence make this a spellbinding cinematic experience that won't be forgotten. The spectacular animation effects by Willis O'Brien astonished audiences in 1925 and the plot which anticipates his later masterpiece, King Kong (a brontosaurus goes on a rampage through the streets of London), make this film an influential classic.

Harry Hoyt directed the first film version of the dinosaur-inhabited land that time forgot, featuring wonderful early stop-motion animation by Willis O'Brien. The silent film, based on a story by Sir Arthur Conan Doyle, features Lewis Stone and the great Wallace Beery as Professor Challenger, as the intrepid explorers who travel to a remote jungle of Brazil to prove the Professor's theories that some prehistoric life might yet still remain. When the company is attacked by an apelike human, they begin to believe, but they have yet to meet the terror and wonder of the supposedly lost Allosaurus, Stegosaurus and Pterodactyl, sixty-five million years past their expiration date!