Ceratosaurus nasicornis
Pronounced seh-RAT-oh-SORE-us nay-zih-KOR-nis
Ceratosauria · Ceratosauridae
A horned predator from the Late Jurassic Morrison Formation of the western United States, a smaller neighbour of Allosaurus with a blade-like horn on its nose, very long upper teeth and a row of small bony plates along its back.
- Bipedal
- Horned
- Armored
- Period
- Jurassic· Kimmeridgian
- Diet
- Carnivore
- Length
- 5.3–7 m
- Mass
- 418–670 kg
- Location
- Colorado, Utah, United States
Quick answers
- How big was Ceratosaurus nasicornis?
- Ceratosaurus nasicornis was about 5.3–7 m long. It stood about 1.6–2 m tall at the hips. It weighed about 418–670 kg. (Wikipedia: Ceratosaurus 2026; Paul 2016)
- When did Ceratosaurus nasicornis live?
- Ceratosaurus nasicornis lived during the Late Jurassic, about 152.2–145.1 million years ago. (Paleobiology Database: Ceratosaurus occurrences 2026)
- Where have Ceratosaurus nasicornis fossils been found?
- Fossils of Ceratosaurus nasicornis have been found in Morrison Formation (Colorado) and United States. (Marsh 1884; Paleobiology Database: Ceratosaurus occurrences 2026)
- What did Ceratosaurus nasicornis eat?
- Ceratosaurus nasicornis was a carnivore. (Marsh 1884; Paleobiology Database: Ceratosaurus occurrences 2026)
- Who named Ceratosaurus nasicornis, and when?
- Ceratosaurus nasicornis was described by Othniel Charles Marsh in 1884. (Marsh 1884; Paleobiology Database: Ceratosaurus occurrences 2026)
- Was Ceratosaurus nasicornis in Jurassic Park?
- Yes. Ceratosaurus nasicornis appears in Jurassic Park III (2001). A brief appearance in Jurassic Park III. Its nose horn and the bony horns over its eyes are genuine features of the skull. (Wikipedia: Dinosaurs in Jurassic Park 2026; Wikipedia: Ceratosaurus 2026)
On this page
- Period
- Jurassic152.2–145.1 Ma
- Diet
- Carnivore
- Length
- 5.3–7 m
- Mass
- 0.4–0.7 t
- Location
- United States
- Classification
- Ceratosauria · Ceratosauridae
- Described
- 1884, Othniel Charles Marsh
Overview
Ceratosaurus nasicornis lived in western North America in the Late Jurassic. Its type skeleton was dug up in 1883-1884 by the farmer Marshall Parker Felch at Garden Park, Colorado, and Othniel Charles Marsh named it in 1884. The skeleton is at the Smithsonian.
It was a medium-sized theropod, around 5 to 7 m long, with a crest-like horn on the snout, bony ridges over the eyes and remarkably long, blade-shaped teeth in the upper jaw. Unlike most theropods it had a row of small osteoderms along the midline of its back.
Ceratosaurus is also known from Utah and from the Lourinhã Formation of Portugal. Two further species named in 2000 are usually treated as the same species. Its closest relatives are the ceratosaurs of the southern continents, such as Carnotaurus.
Name meaning
"Horned lizard", from Greek keras ("horn") and sauros ("lizard"); nasicornis, Latin for "nose horn" (Marsh 1884).
Biology & evidence
What scientists think about how this animal lived, and how strong the evidence for each idea is.
Skin & covering
Ceratosaurus had a row of small bony plates along its back.
Evidence level: Direct evidenceSmall osteoderms are preserved along the midline, a feature unknown in most other theropods.
Evidence for / against · 1
Evidence for
Specimen · Ceratosaurus nasal horn and osteoderms
A blade-like horn on the fused nasal bones (about 13 cm long in the holotype) and a row of small osteoderms along the back midline.
Specimen: USNM 4735
Behavior
The nose horn of Ceratosaurus was used for display rather than fighting.
Evidence level: HypothesisThe horn is thin and blade-like, which suits display better than combat; its real use is unknown.
Evidence for / against · 1
Evidence for
Specimen · Ceratosaurus nasal horn and osteoderms
A blade-like horn on the fused nasal bones (about 13 cm long in the holotype) and a row of small osteoderms along the back midline.
Specimen: USNM 4735
Size
- Length
- 5.3–7 m
- Height
- 1.8 mpublished range 1.6–2 m
- Mass
- 418–670 kg
(23 ft)
Based on USNM 4735 (5.3-5.7 m); larger individuals about 7 m
(5.9 ft)
Based on USNM 4735 (holotype) to larger BYU material
Based on USNM 4735
Timeline
Periods: Kimmeridgian (154.8–149.2 Ma), Tithonian (149.2–145 Ma), Late Jurassic (161.5–145 Ma)
Late Kimmeridgian-early Tithonian bounds of the type collection in PBDB (Brushy Basin Member, Morrison Formation).
Location
Formations
- Morrison Formation · Colorado
- Felch Quarry, Garden Park, near Cañon City, Colorado · Morrison Formation · Colorado · position approximate
These are the places where fossils have been found, not the full area where the animal lived.
Ecosystem
Lived in: Morrison
156–147 million years ago · floodplain, river system, open woodland, lake
A vast, seasonally dry floodplain crossed by rivers in the western interior of North America in the Late Jurassic, with a wet and a dry season, conifer and fern vegetation along the water and giant sauropods in abundance.
Same ecosystem
Same ecosystem
Same ecosystem
Same ecosystem
Same ecosystem
Same ecosystem
Classification
- cladeDinosauria
- cladeSaurischia
- cladeTheropoda
- cladeNeotheropoda
- cladeCeratosauria
- familyCeratosauridae
- genusCeratosaurus
- speciesCeratosaurus nasicornis
Taxonomic status: Valid
Fossil record
| Catalog number | Status | Institution | Found |
|---|---|---|---|
| USNM 4735 | Holotype | National Museum of Natural History, Smithsonian Institution (USNM) | 1883 |
What has been found
Holotype: USNM 4735
- Preserved
- Partial
- Reconstructed
- Unknown / not recorded
Region by region (table)
| Region | State |
|---|---|
| Skull | Preserved · With the nasal horn. |
| Mandible | Unknown / not recorded |
| Teeth | Unknown / not recorded |
| Cervical vertebrae | Unknown / not recorded |
| Dorsal vertebrae | Unknown / not recorded |
| Sacrum | Unknown / not recorded |
| Caudal vertebrae | Unknown / not recorded |
| Ribs | Unknown / not recorded |
| Gastralia | Unknown / not recorded |
| Scapula / shoulder girdle | Unknown / not recorded |
| Humerus | Unknown / not recorded |
| Forearm (radius / ulna) | Unknown / not recorded |
| Hand (manus) | Unknown / not recorded |
| Pelvis | Unknown / not recorded |
| Femur | Unknown / not recorded |
| Tibia / fibula | Unknown / not recorded |
| Foot (pes) | Unknown / not recorded |
Gallery
Discovery
- Year described
- 1884
- Described by
- Othniel Charles Marsh
- Type specimen
- USNM 4735
Discovery timeline
1883 · First material found
Felch excavates the Ceratosaurus skeleton
The farmer Marshall Parker Felch digs the skeleton at Garden Park, Colorado, for Marsh (1883-1884).
People: Marshall P. Felch
1884 · Formally described
Marsh names Ceratosaurus nasicornis
Marsh names the horned theropod in his series on American Jurassic dinosaurs.
People: Othniel Charles Marsh
In Jurassic Park & Jurassic World
Films
- Jurassic Park III (2001)
On screen
A brief appearance in Jurassic Park III.
Film vs fossils
- Its nose horn and the bony horns over its eyes are genuine features of the skull.
Film titles are used for identification only. DinoDex is not affiliated with or endorsed by the Jurassic Park / Jurassic World franchise. All dinosaurs seen in the films
Sources
- (2026). Paleobiology Database: Ceratosaurus occurrences. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/occs/list.txt?base_name=Ceratosaurus&show=coords,paleoloc,strat,loc,ref&pgm=gplates (opens in a new tab)
- (2026). Wikipedia: Ceratosaurus. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Ceratosaurus (opens in a new tab)
- (2026). Wikipedia: Dinosaurs in Jurassic Park. Wikipedia. https://en.wikipedia.org/wiki/Dinosaurs_in_Jurassic_Park (opens in a new tab)
- Marsh, O. C. (1884). Principal characters of American Jurassic dinosaurs. Part VIII. The order Theropoda. American Journal of Science, series 3, 27: 329-340. doi:10.2475/ajs.s3-27.160.329 (opens in a new tab)
- Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.