Rhedosaurus is a fictional dinosaur that first appeared in the 1953 film "The Beast from 20,000 Fathoms." It is depicted as a large, prehistoric reptile awakened by nuclear testing in the Arctic. The creature is characterized by its massive size, spiky back, and a long tail, resembling a mix of a dinosaur and a dragon. In the film, Rhedosaurus wreaks havoc in New York City, showcasing its destructive power. The creature is often associated with the genre of science fiction and monster movies, highlighting the fears of the time regarding nuclear energy and its potential consequences on nature and humanity.