page_title: Ceratosaurus
section_title: Holotype specimen of C.  nasicornis
hierarchical_section_title: Ceratosaurus / History of discovery / Holotype specimen of C.  nasicornis
caption_attribution_description: Skeleton of Ceratosaurus, a theropod dinosaur.
context_page_description: Ceratosaurus was a carnivorous theropod dinosaur in the Late Jurassic period. This genus was first described in 1884 by American paleontologist Othniel Charles Marsh based on a nearly complete skeleton discovered in Garden Park, Colorado, in rocks belonging to the Morrison Formation. The type species is Ceratosaurus nasicornis.
  The Garden Park specimen remains the most complete skeleton known from the genus, and only a handful of additional specimens have been described since. Two additional species, Ceratosaurus dentisulcatus and Ceratosaurus magnicornis, have been described in 2000 from two fragmentary skeletons from the Cleveland-Lloyd Quarry of Utah and from the vicinity of Fruita, Colorado. The validity of these additional species has been questioned, however, and all three skeletons possibly represent different growth stages of the same species. In 1999, the discovery of the first juvenile specimen was reported. Since 2000, a partial specimen was excavated and described from the Lourinhã Formation of Portugal, providing evidence for the presence of the genus outside of North America.
context_section_description: The first specimen, the holotype USNM 4735, was discovered and excavated by farmer Marshall Parker Felch in 1883 and 1884. Found in articulation, with the bones still connected to each other, it was nearly complete, including the skull. Significant missing parts include an unknown number of vertebrae; all but the last ribs of the trunk; the humeri (upper arm bones); the distal finger bones of both hands; most of the right fore limb; most of the left hind limb; and most of the feet. The specimen was found encased in hard sandstone; the skull and spine had been heavily distorted during fossilization. The site of discovery, located in the Garden Park area north of Cañon City, Colorado, and known as the Felch Quarry 1, is regarded as one of the richest fossil sites of the Morrison Formation. Numerous dinosaur fossils had been recovered from this quarry even before the discovery of Ceratosaurus, most notably a nearly complete specimen of Allosaurus (USNM 4734) in 1883 and 1884.
  After excavation, the specimen was shipped to the Peabody Museum of Natural History in New Haven, where it was studied by Marsh, who described it as the new genus and species Ceratosaurus nasicornis in 1884. The name Ceratosaurus may be translated as "horn lizard" (from Greek κερας/κερατος,  keras/keratos—"horn" and σαυρος/sauros—"lizard"), and nasicornis with "nose horn" (from Latin nasus—"nose" and cornu—"horn"). Given the completeness of the specimen, the newly described genus was at the time the best-known theropod discovered in America. In 1898 and 1899, the specimen was transferred to the National Museum of Natural History in Washington, DC, together with many other fossils originally described by Marsh. Only part of this material was fully prepared when it arrived in Washington; subsequent preparation lasted from 1911 to the end of 1918. Packaging and shipment from New Haven to Washington caused some damage to the Ceratosaurus specimen. In 1920, Charles Gilmore published an extensive redescription of this and the other theropod specimens received from New Haven, including the nearly complete Allosaurus specimen recovered from the same quarry.
  In an 1892 paper, Marsh published the first skeletal reconstruction of Ceratosaurus, which depicts the animal at 22 ft (6.7 m) in length and 12 ft (3.7 m) in height. As noted by Gilmore in 1920, the trunk was depicted much too long in this reconstruction, incorporating at least six dorsal vertebrae too many. This error was repeated in several subsequent publications, including the first life reconstruction, which was drawn in 1899 by Frank Bond under the guidance of Charles R. Knight, but not published until 1920. A more accurate life reconstruction, published in 1901, was produced by Joseph M. Gleeson, again under Knight's supervision. The holotype was mounted by Gilmore in 1910 and 1911, and since then was exhibited at the National Museum of Natural History. Most early reconstructions show Ceratosaurus in an upright posture, with the tail dragging on the ground. Gilmore's mount of the holotype, in contrast, was ahead of its time: Inspired by the upper thigh bones, which were found angled against the lower leg, he depicted the mount as a running animal with a horizontal rather than upright posture and a tail that did not make contact with the ground. Because of the strong flattening of the fossils, Gilmore mounted the specimen not as a free-standing skeleton, but as a bas-relief within an artificial wall. With the bones being partly embedded in a plaque, scientific access was limited. In the course of the renovation of the museum's dinosaur exhibition between 2014 and 2019, the specimen was dismantled and freed from the encasing plaque. In the new exhibition, which is set to open in 2019, the mount is planned to be replaced by a free-standing cast, and the original bones to be stored in the museum collection to allow full access for scientists.
caption: C. nasicornis skeleton restoration by Othniel Charles Marsh from 1892, depicted in an erroneous upright position and with excess vertebrae in the spine resulting in an overly elongated trunk
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