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Image gallery for Rhedosaurus

Production picture of the Rhedosaurus model used in The Beast from 20,000 Fathoms
Name information
Alternate names DinosaurTFH, Rhedo, Rhedosaur,[1]
The Beast, Herman[2]
Subtitle(s) Atomic Monster
(原子怪獣,   Genshi Kaijū)[3]
Physical information
Species Dinosaur; extraterrestrial dinosaurPoD
Height ~90-100 feetTFH
Length ~200 feetTBf2KF[1]
Weight 500 tonsTBf2KF[1]
Affiliation information
Place(s) of emergence Baffin Bay, the ArcticTBf2KF
Enemies Humans, Tyrannosaurus rexPoD
Real world information
Written by Lou Morheim, Fred Freiberger,
Ray Bradbury, Daniel James,
Eugène Lourié, Robert Smith
Designed by Ray Harryhausen[4]
Modeled by Ray Harryhausen,TBf2KF[4]
Stephen CzerkasPoD
Other information
First appearance Latest appearance
The Beast from
20,000 Fathoms
Planet of Dinosaurs
1953:1977:More roars

The Rhedosaurus is a giant fictional dinosaur who serves as the antagonist of the 1953 American giant monster film The Beast from 20,000 Fathoms. It is based on a creature from the short story "The Fog Horn."


According to Rhedosaurus creator Ray Harryhausen, the monster's name may have been devised by The Beast from 20,000 Fathoms producer Hal Chester or one of the film's writers. He went on to say that some people believe the first two letters of Rhedosaurus's name were inspired by his initials, R. H.[5] The beast has also been nicknamed Herman,[2] and is sometimes referred to as a "Rhedosaur."[1]


Ray Harryhausen created a clay model of the Rhedosaurus based on sketches that he made for The Beast from 20,000 Fathoms, but he and some of the staff working on the film felt that his model was "too kind, too babyish."[4] Thus, Harryhausen returned to his workshop to make a stronger, more terrifying version of the model. The new model was tested, but Harryhausen felt that it still wasn't right, so he decided to rebuild the model once again after a discussion with the film's two producers, Jack Dietz and Hal E. Chester.[4] This model was ultimately used in the film. Harryhausen also designed and supervised most of the miniatures used in the film such as the lighthouse, the harbor landing stage, and sections of the Coney Island roller-coaster where the Rhedosaurus is killed at the end of the film.[4]

A five-second piece of stop-motion animation of the Rhedosaurus cut from the film appeared in the trailer for The Black Scorpion, released in 1957.[6] The following year, Harryhausen repurposed parts of the Rhedosaurus model for the fire-breathing dragon in The 7th Voyage of Sinbad.[7][8]

For Planet of Dinosaurs, Stephen Czerkas constructed a new, smaller model that was used to battle, and ultimately be killed by, a Tyrannosaurus rex. According to animator Jim Aupperle, "Stephen and I both place the Rhedosaurus among our top favorite of Ray's myriad monsters. We felt that by giving the great Beast a cameo in our film we were acknowledging the immense debt we both feel to Ray. We had to make the Rhedosaurus more of a baby size because one as large as the original would have made a meal of our Tyrannosaurus instead of the other way around."[9] Harryhausen visited the set during filming.[9]


The creature from "The Fog Horn," upon which the Rhedosaurus is based, is said to have a 40-foot long neck, a body covered in crayfish and other sea life, and a tail only barely seen.

In The Beast from 20,000 Fathoms, the Rhedosaurus has a quadrupedal build, with a long tail and forelimbs noticeably longer than its hindlimbs. Its back is adorned with a single row of backward-facing spikes that continue from its scalp to its tail. Crocodilian scales line down its underside while bumpy, pebble-like scales cover the remainder of the body. Its snout is short with large nostrils and noticeable fangs.

In Planet of Dinosaurs, the Rhedosaurus has a slimmer skull and a slightly longer neck. Its skin is brown.


In The Beast from 20,000 Fathoms, the Rhedosaurus was the only surviving member of its species, buried beneath the ice in the Arctic for 100 million years until it was reawakened by a nuclear bomb test in the modern day.


The Beast from 20,000 Fathoms

Following a nuclear bomb test in the Arctic, a gigantic dinosaur known as a Rhedosaurus breaks free from its state of suspended animation in the ice and heads down the North American coast, destroying everything in its path as it makes its way to New York City, its original home. The Rhedosaurus wandered the streets, eating anyone who got too close to it. Attempts to kill it were complicated by an ancient disease it carried; spilling its blood freed the plague, which was almost as deadly as the reptile itself. The Rhedosaurus was eventually killed at Coney Island when a radioactive isotope was shot into a wound on its neck, both fatally wounding it and also neutralizing the disease. As the Rhedosaurus succumbed to the isotope, a fire it started by destroying the machinery of a roller coaster spread across the island. The Rhedosaurus burst free of the burning coaster and roared out defiantly, before finally collapsing to the ground, dead.

Planet of Dinosaurs

The Rhedosaurus in Planet of Dinosaurs

As a Tyrannosaurus rex began menacing Captain Lee's crew, Lee and Jim broke into an argument over who should be in charge of crafting a plan to kill it. To prove his resolve, Lee baited the Tyrannosaurus into chasing him away from the camp when the trap preparations were not yet ready. As he continued to run, he took shelter under a ledge, above which a car-sized Rhedosaurus appeared. It hissed at Lee but did not chase him as he continued running. The pursuing Tyrannosaurus came upon the Rhedosaurus and roared at it. The Rhedosaurus roared back, prompting the Tyrannosaurus to lunge at it and bite it on the shoulder, carrying it in the air for several seconds as the Rhedosaurus struggled and tried to fight back. The conflict was ended when the Tyrannosaurus set the Rhedosaurus on the ground and quickly bit into its head, crushing its skull and killing it before carrying the body back to its lair to feed on it, giving Lee enough time to return to his crew and plan the counterattack against the dinosaur.


Contaminated blood

The Rhedosaurus's blood is host to a prehistoric virus. As the human immune system has no basis to defend against it, any exposed to it become fatally ill which forbids the use of heavy ordinance.

Physical abilities

The Rhedosaurus primarily relies on its sheer bulk and powerful limbs during combat, shown when it topples over a lighthouse and crushes a car like it was an insect underneath its metaphorical boot. Its jaws were able to kill and eat a human in one bite as well.


The Rhedosaurus's scales were thick enough to be unharmed by small arms fire, though heavier munitions were able to wound it sufficiently enough to be able to kill it.

Short stories

"The Fog Horn"

In the short story "The Fog Horn", which was adapted as The Beast from 20,000 Fathoms, a large, dinosaur-like creature with a longer neck, but otherwise similar to the Rhedosaurus, appears from the depths, attracted to a lighthouse and the sound of its fog horn. The creature first appeared circling the lighthouse, but left soon after. Exactly one year later, the creature reappeared and started calling out to the lighthouse. When the fog horn stopped calling back, the creature attacked and destroyed the lighthouse, then went back into the ocean, never to return.


Main article: Rhedosaurus/Gallery.

In other languages

Language Name Meaning
Flagicon Japan.png Japanese リドサウルス Ridosaurusu Transcription of English name
Flagicon Portugal.png Portuguese Rhedossauro Adapted from English name, Portuguese -ssauro in place of -saurus
Flagicon Spain.png Spanish Rhedosaurio Adapted from English name, Spanish -saurio in place of -saurus


In The Beast from 20,000 Fathoms, the Rhedosaurus's roars are derived from the sound effects of a wild horse used in the 1952 film The Lion and the Horse.[10]

In the short story "The Fog Horn", its roar is said to be like the sound of a lighthouse's fog horn.

The Rhedosaurus's roars


  • The Rhedosaurus, along with King Kong, was one of the main inspirations for Godzilla. During the production of the 1954 film Godzilla, its pre-published storyline was very similar to that of The Beast from 20,000 Fathoms and was actually titled The Giant Monster from 20,000 Miles Under the Sea (海底二万哩から来た大怪獣,   Kaiteinimanmairu kara Kita Daikaijū).[11] Rhedosaurus creator Ray Harryhausen considered Godzilla to be a "filch" of his own work.[12]
  • The Rhedosaurus is featured in posters for the 1953 3D science-fiction film Robot Monster, which was released to American theaters on June 10, three days before The Beast from 20,000 Fathoms was released.
  • A creature resembling the Rhedosaurus briefly appeared in the 1970 film When Dinosaurs Ruled the Earth, though whether it is meant to be an homage to the Rhedosaurus is unknown.
  • In Gremlins 2: The New Batch, two Gremlins briefly watch The Beast from 20,000 Fathoms on TV, laughing during the scene when the Rhedosaurus eats a police officer.
  • The Rhedosaurus appeared in the sixth episode of the second season of the ABC TV improvisational series Whose Line Is It Anyway?.
  • Batman #104 (December 1956), in its third story (of three total) and the one on the front cover, "The Creature from 20,000 Fathoms!", features a creature named Bobonga that pays homage to the Rhedosaurus, along with the story's title.
  • In the American television comedy series It's Always Sunny in Philadelphia, a postcard featuring a screenshot of the Rhedosaurus from The Beast from 20,000 Fathoms is displayed in the background during the episode "Mac's Mom Burns Her House Down" (season six, episode six) which originally aired on October 21, 2010.
  • A dinosaur modeled on the Rhedosaurus appears in issues #2 and 4 of the 2013 5-issue comic book miniseries Dinosaurs Attack! by IDW Publishing. In issue #2, after manifesting in Italy, it battles a dinosaur modeled on the Paleosaurus from The Giant Behemoth (which also manifests in the same area) at the Leaning Tower of Pisa, where it is shoved through the tower by its rival. In issue #4, it appears alongside several creatures as part of a charge against the U.S. military forces, with some of them resembling dinosaurian characters such as Godzilla (who leads the charge), Rodan, the Paleosaurus, Gorgo, Reptilicus, and Gertie the Dinosaur, among others.[13]
    • The Rhedosaurus also appears together with the Paleosaurus in card #10 (of 55) of the Topps trading card series Dinosaurs Attack! (which was the basis for the above-mentioned miniseries), "Italy Under Seige [sic]!". The two dinosaurs are shown fighting each other at the Leaning Tower of Pisa in Italy.

See also


This is a list of references for Rhedosaurus. These citations are used to identify the reliable sources on which this article is based. These references appear inside articles in the form of superscript numbers, which look like this: [1]

  1. 1.0 1.1 1.2 1.3 Webber 2004, p. 50
  2. 2.0 2.1 Hankin 2008, p. 76
  3. "原子怪獣現わる [DVD]". Amazon. Retrieved 7 November 2021.
  4. 4.0 4.1 4.2 4.3 4.4 Harryhausen & Dalton 2006, p. 74
  5. Harryhausen & Dalton 2003, p. 49.
  6. Berry 2005, p. 33.
  7. Berry 2005, p. 36.
  8. Webber 2004, p. 52.
  9. 9.0 9.1 Harryhausen & Dalton 2008, p. 190.
  10. Neuhaus, Lederman & Zito 1998, p. 53.
  11. Kabuki 1998, p. 34-38
  12. Shaw, William (20 November 2005). "The Origin of the Species". The Guardian. Retrieved 9 December 2021.
  13. Dinosaurs Attack Homages.jpg



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