# Ceratosaurus nasicornis

> 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.

- Classification: Dinosauria (clade) > Saurischia (clade) > Theropoda (clade) > Neotheropoda (clade) > Ceratosauria (clade) > Ceratosauridae (family) > Ceratosaurus (genus) > Ceratosaurus nasicornis (species)
- Length: 5.3–7 m
- Hip height: 1.6–2 m
- Mass: 418–670 kg
- Age: 152.2–145.1 million years ago (Late Jurassic)
- Fossils found in: Morrison Formation (Colorado); United States
- Diet: carnivore
- Described: Othniel Charles Marsh, 1884
- In films: Jurassic Park III (2001)

Canonical page: https://dinodex.club/dinosaurs/ceratosaurus-nasicornis
Last updated: 2026-09-27

## 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).

## Sources

1. (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
2. (2026). Wikipedia: Ceratosaurus. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Ceratosaurus
3. Marsh, O. C. (1884). Principal characters of American Jurassic dinosaurs. Part VIII. The order Theropoda. American Journal of Science, series 3, 27: 329-340. https://doi.org/10.2475/ajs.s3-27.160.329
4. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.

---

Cite as: "Ceratosaurus nasicornis". DinoDex. https://dinodex.club/dinosaurs/ceratosaurus-nasicornis (updated 2026-09-27).