In 1850, Gideon Mantell decided that "C. conybeari" was so different from "Cetiosaurus" that it needed a new genus, so he reclassified it under the new name "Pelorosaurus conybeari". Mantell had originally, in November 1849, intended to use the name "Colossosaurus", but upon discovering that "kolossos" was Greek for "statue" and not "giant", he changed his mind. The generic name is derived from the Greek "pelor", "monster". He also emended the specific name (honouring William Conybeare) to "conybearei", but under the present rules of the ICZN, the original "conybeari", today written without a capital, has priority. Mantell not only used the sauropod material of "C. brevis" as the type of "Pelorosaurus conybeari" but also a large humerus found by miller Peter Fuller at the same site, BMNH 28626, which he assumed to have been of the same individual, being discovered only a few metres away from the vertebrae. Mantell acquired the bone for £8. The humerus, clearly shaped to vertically support the weight of the body and presumed to possess a medullary cavity, showed that "Pelorosaurus" was a land animal. This was a main motive in naming a separate genus; shortly afterwards, however, by studying the sacral vertebrae of "Cetiosaurus" Mantell established that it too lived on land.