Pelorosaurus conybeari is the name given to a few sauropod dinosaur bones from the Lower Cretaceous period, about 138–112 million years ago.
Bones of Pelorosaurus have been found in England and Portugal. It was a Brachiosaur, with front legs that were longer than its hind legs.
The name has been challenged, and has been the subject of long-lasting dispute. Some palaeontologists prefer the name Cetiosaurus brevis.
The taxonomic status of Pelorosaurus is as a result very problematic. Technically, Cetiosaurus brevis is its type species. The position of Pelorosaurus is further undermined by the fact that several researchers hold that the genus is a nomen dubium ('doubtful name').
Pelorosaurus was one of the first dinosaurs described, and the naming procedures were not so well-developed at the time. Its life-style is assumed to be similar to other brachiosaurs, eating from the higher branches of tall conifer trees.