The journal of explorer Maple White is recovered from a plateau in South America featuring sketches of dinosaurs, which is enough proof for the eccentric Professor Challenger that dinosaurs still walk the earth. With that, John Roxton (sportsman), news reporter Edward Malone (whom wishes to go on the expedition to impress his fiance'), Challenger and Paula White (as well as an Indian servant, Zambo) leave for the plateau. They get onto the plateau by cutting down a tree and using it as a bridge, but it is knocked over by a brontosaurus, leaving them trapped. The explorers are shocked when they discover that a large rock has been sent their way by an ape-man perched on top of a ledge. As the crew look up to see their attacker, Challenger spies a Pteranodon (mistakenly referred to as a pterodactyl in the film) overhead and proves that the statement in Maple White's diary is true. The explorers witness various life-and-death struggles between the prehistoric beasts of the plateau. During which, an Allosaurus makes its way to the camp site and attacks the exploration party. It is finally driven off by Ed Malone who throws a burning torch into the beast's mouth. Convinced that the camp isn't safe, Ed Malone climbs a tree to search for a new location, but is attacked by the ape-man. John Roxton succeeds in shooting the ape man, but the creature is merely wounded and escapes before John can finish him off. The explorers then make preparations to live on the plateau potentially indefinitely. A catapult is constructed and a in search for Maple White, his remains are found confirming his death. It is at this time that Ed confesses his love for Paula and the two are unofficially wed. Shortly afterwards, as the paleontologists are observing a Brontosaurus, it is attacked by an allosaur and falls off the edge of the plateau, becoming trapped in a mud bank. Soon afterwards, a volcano erupts, causing a mass stampede among the giant beasts of the prehistoric world. In the end, the crew is saved when Paula White's pet monkey Jocko climbs a rope up the plateau and the crew climb down. As Ed makes his descent, he is again attacked by the ape-man who pulls the rope later. The ape-man is again shot, and this time killed, by Sir John Roxton. The Brontosaurus that was pushed off the plateau had landed softly in the mud at the bottom of the plateau, and Challenger manages to bring it back to London, as he wants to put it on display. However, it escapes and causes havoc until it reaches Tower Bridge, where it's massive weight causes it to break through, into the English channel where it swims away. Challenger is morose as the creature leaves, whereas Edward Malone discovers that the love he left in London has married in his absence, allowing him and Paula to be together. It is now Roxton's turn to be morose.
Cast/Characters in The Lost World
- Sir Arthur Conan Doyle – Himself (appears in a frontispiece to the film)
- Bessie Love – Paula White
- Lewis Stone – Sir John Roxton
- Lloyd Hughes – Edward Malone
- Wallace Beery – Professor Challenger
- Arthur Hoyt – Professor Summerlee
- Alma Bennett – Gladys Hungerford
- Virginia Browne Faire – Marquette the half-cast girl (uncredited)
- Bull Montana – Ape Man/Gomez
- Francis Finch-Smiles (billed as "Finch Smiles") – Austin
- Jules Cowes (in blackface) – Zambo
- Margerette McWade – Mrs. Challenger
- George Bunny – Colin McArdle
- Charles Wellesly – Major Hibbard (uncredited)
- Nelson MacDowell – Attorney (uncredited)
- Chris-Pin Martin – Bearer/Cannibal (Scenes Deleted)
- Jocko the Monkey – Himself
- Mary the Chimpanzee – Herself (uncredited)
Note: All human cast members who are listed in the on-screen credits are billed as "Mr..." or "Miss...."
- Agathaumas (seen in battle with both Allosaurus and Tyrannosaurus)
- Allosaurus (main carnivorous dinosaur seen,attacking Trachodon and Brontosaurus among others)
- Ape man (menaces the team of explorers)
- Brontosaurus (after falling into a bog after an Allosaurus attack, one is captured and taken to civilization, where it escapes and terrorizes the city)
- Pteranodon (the first prehistoric animal seen by the team of explorers)
- Stegosaurus (escaped the volcanic eruption with many other animals)
- Trachodon (is preyed upon by the Allosaurus)
- Triceratops (seen in large herds,and shown to be capable of handling Allosaurus in battle)
- Tyrannosaurus (is seen to have little trouble bringing down Agathaumas,as well as having a taste for any Pteranodon that swoops in too close)
(The film's program gives mention of the Diplodocus but none are shown in the surviving footage.)
Other animals on the plateau
- Capuchin Monkey
- Unidentified lizards with frills and feathers
Animals seen in the Amazon, but not the plateau
- Caiman or Alligator
- Marsh Deer
- Jaguar (stock footage)
- Spectacled Bears
- South American Tree Sloth (stock footage)
Restorations of The Lost World
- George Eastman House - Laserdisc preservation with stills showing missing scenes
- George Eastman House - Film restoration using materials from Czechoslovakian archive. Many sequences still missing and some inadvertently left out
- David Shepard, Serge Bromberg - DVD restoration using Kodascope prints, Czechoslovakian archive materials, and trailers.
Missing or Deleted Scenes
- Sir Arthur Conan Doyle sits at his desk, writing The Lost World (footage of Doyle, found in some copies, was taken from a 1927 interview)
- Ed Malone sees three people sent to interview Challenger, bruised and bandaged
- Ed Malone escapes from Challenger in the Zoological Museum by climbing on the back of the Brontosaurus skeleton
- The explorers are attacked by cannibals
- The native bearers, lead by Gomez, mutiny and injure Zambo's arm
- Challenger scrambles onto railing of bridge to watch the Brontosaurus swim out to sea
Scenes rediscovered but not added back
- A Brontosaurus feeds on some leaves
- A Triceratops family enjoy each other's company
- An Allosaurus is distraught over a Brontosaurus escaping over a cliff
- Two brontosaurs have a confrontation
- A Triceratops herd is seen with an Allosaurus in the background
- A Trachodon eats while an Allosaurus stalks it from the background
- An Agathaumas and Stegosaurus battle over space
(These can be found as animation outtakes on some DVD copies)
- In 2004 an incomplete, original tinted/toned/hand-colored nitrate 35 mm print of the original version of The Lost World was discovered and purchased by Film Preservation Associates.
- Willis O'Brien combined animated dinosaurs with live-action footage of human beings, but at first he was able to do this only by separating the frame into two parts (also known as split screen). As work went on, O'Brien's technique grew better and he could combine live-action and stop-motion footage in the same part of the screen.
- In 1922, Conan Doyle showed O'Brien's test reel to a meeting of the Society of American Magicians, which included Harry Houdini. The astounded audience watched footage of a Triceratops family, an attack by an Allosaurus and some Stegosaurus footage. Doyle refused to discuss the film's origins. On the next day, the New York Times ran a front page article about it, saying "(Conan Doyle’s) monsters of the ancient world, or of the new world which he has discovered in the ether, were extraordinarily lifelike. If fakes, they were masterpieces".
- The dinosaurs of this film were based on the artwork of Charles R. Knight.
- Some of the dinosaur models used in the film came into the famous collection of the fantasy lover Forrest J Ackerman. The models were not specially preserved, and with time the rubber dried out and fell to pieces, leaving only the metallic armatures.
- The Lost World became the first film to be shown to airline passengers. This happened in April 1925 on a London-Paris flight by the company Imperial Airways. As film stock of the era was nitrate and highly flammable, this was a risky undertaking on a wood and fabric-hulled plane.
- This was the first feature length film made in the United States, possibly the world, to feature model animation as the primary special effect, or stop motion animation in general.
- This is the first dinosaur-oriented film hit, and it led to other dinosaur movies, from King Kong to the Jurassic Park trilogy.