Cetiosaurus, carries a meaning of “whale lizard,” derived from the Greek words "keteios", signifying “sea monster” (later interpreted as “whale”), and "sauros", which denotes “lizard.” This genus belongs to the herbivorous sauropod dinosaurs and existed during the Middle Jurassic Period, approximately 168 million years ago, in the area that is now recognized as Britain.

Notably, Cetiosaurus holds the distinction of being the first sauropod from which bones were described, dating back to 1842. It also stands as the most extensively preserved sauropod discovered in England. In common with all sauropods, Cetiosaurus was a long-necked, quadrupedal creature. Its neck, although moderately long, did not surpass the length of its body. In contrast, its tail was considerably longer, composed of a minimum of forty caudal vertebrae.

The dorsal vertebrae, situated along its back, featured a solid, non-air-chambered structure, differing from the highly hollowed bones seen in later sauropods like Brachiosaurus. Cetiosaurus exhibited forelimbs equal in length to its hindlimbs, a characteristic that set it apart from most other sauropods. For instance, its forearm matched the upper arm in length, resulting in a forelimb that was as long as the hindlimb. Additionally, its thigh bone measured approximately six feet in length.