Genus: Gigantosaurus SEELEY, 1869 (nomen dubium)
Etymology: Greek, gigant- (gigas) “giant” and Greek, sauros, “lizard”: “Giant lizard”.

Species: megalonyx SEELEY, 1869 (nomen dubium)
Etymology:
= Pelorosaurus megalonyx (SEELEY, 1869) OLSHEVSKY, 1991 (nomen dubium)

Holotype: Woodwardian Museum J 29477

Locality: Between Sandsfoot and Portland Ferrry-bridge, Dorset County, England, Southern United Kingdom.

Horizon:

Biostratigraphy:

Age: Kimmeridgian Stage, Middle Malm Epoch, Late Jurassic.

Material: 1 cervical centrum?

Referred material:

Locality: Roswell Pits, Ely, (TL 555808, TL 552807), Cambridgeshire County, England, Southern United Kingdom.

Horizon: Lower Kimmeridge Clay.

Biostratigraphy:

Age: Lower Kimmeridgian Stage, Middle Malm Epoch, Late Jurassic.

Material:

Number: Not given: ?proximal end of a tibia.

or

NHMUK (old BMNH) 32498-99: Fibula and terminal phalanx.

Locality: Unknown, England, Southern United Kingdom.

Horizon:

Biostratigraphy:

Age: Kimmeridgian Stage, Middle Malm Epoch, Late Jurassic.

Material:

Number: Not given: 3 caudal vertebrae, and a cast of a larger caudal.