"Ceratosaurus" followed the body plan typical for large theropod dinosaurs. A biped, it moved on powerful hind legs, while its arms were reduced in size. Specimen USNM 4735, the first discovered skeleton and holotype of "Ceratosaurus nasicornis", was an individual or in length according to separate sources. Whether this animal was fully grown is not clear. Othniel Charles Marsh, in 1884, suggested that this specimen weighed about half as much as the contemporary "Allosaurus". In more recent accounts, this was revised to , , or . Three additional skeletons discovered in the latter half of the 20th century were substantially larger. The first of these, UMNH VP 5278, was informally estimated by James Madsen to have been around long, but was later estimated at in length. Its weight was calculated at , , and in separate works. The second skeleton, MWC 1, was somewhat smaller than UMNH VP 5278 and might have been in weight. The third, yet undescribed, specimen BYUVP 12893 was claimed to be the largest yet discovered, although estimates have not been published. Another specimen (ML 352), discovered in Portugal in 2000, was estimated at in length and in weight.