likely have been more elongated due to its keratinous sheath. Behind the nasal horn, the nasal bones formed an oval groove; both this groove and the nasal horn serve as features to distinguish Ceratosaurus from related genera. In addition to the large nasal horn, Ceratosaurus possessed smaller, semicircular, bony ridges in front of each eye, similar to those of Allosaurus. These ridges were formed by the lacrimal bones. In juveniles, all three horns were smaller than in adults, and the two halves of the nasal horn core were not yet fused. The premaxillary bones, which formed the tip of the snout, contained merely three teeth on each side, less than in most other theropods. The of the upper jaw were lined with 15 blade-like teeth on each side in the holotype. The first eight of these teeth were very long and robust, but from the ninth tooth onward they gradually decrease in size. As typical for theropods, they featured finely edges, which in the holotype contained some 10 denticles per . Specimen MWC 1 merely showed 11 to 12, and specimen UMNH VP 5278 12 teeth in each maxilla; the teeth were more robust and more recurved in the latter specimen. In all specimens, the tooth crowns of the upper jaws were exceptionally long. In specimen UMNH VP 5278, they measured up to in length, which is equal to the minimum height of the lower jaw. In the holotype, they are in length, which even surpasses the minimum height of the lower jaw. In other theropods, a comparable tooth length is only known from the possibly closely related Genyodectes. In contrast, several members of the Abelisauridae feature very short tooth crowns. In the holotype, each half of the , the tooth-bearing bone of the , was equipped with 15 teeth, which are, however, poorly preserved. Both specimens MWC 1 and UMNH VP 5278 show only 11 teeth in each dentary, which were, as shown by the latter specimen, slightly straighter and less sturdy than those of the upper jaw. Postcranial skeleton The exact number of vertebrae is unknown due to several gaps in the spine of the Ceratosaurus nasicornis holotype. At least 20 vertebrae formed the neck and back in front of the sacrum. In the middle portion of the neck, the (bodies) of the vertebrae were as long as they were tall, while in the front and rear portions