Author's note: these pages were written some years ago. I am not planning to update them. For a more current coverage, see the link to palaeos com Palaeos website (to which many links on these pages point to anyway. More info here

Superfamily Ceratosauroidea

family Ceratosauridae

link to palaeos com Early Jurassic to link to palaeos com Late Jurassic
( link to palaeos com Sinemurian to link to palaeos com Kimmeridgian/ link to palaeos com Tithonian)

Ceratosaurus nasicornis skeleton - length 6 meters
late Jurassic ( link to palaeos com Kimmeridgian)
image courtesy Professor Paul Olsen

My Linnean/Evolutionary Systematic sympathies are showing - I have used the term "Ceratosauroidea" rather than "neoceratosauria" to distinguish these large, persistantly primitive theropods from their Coelophysoid ancestors. Both Coelophysoidea and Ceratosauroidea/Neoceratosauria together from the Ceratosauria, the most primitive clade of "neotheropods" (conventional or non-herrasaur theropods). The Abelisaurs are often included here as well. These are united by a number of features, including a hand with four fingers (the fourth digit is present, although strongly reduced, in ceratosaurs, but absent in all more advanced theropods), the lightly-built jaw support bones and roof of the mouth, and the robust central metatarsal. and a number of more specialised features. However, the "neoceratosaurs" lack many of the skull specializations of the coelophysids, so it is possible that they may not be that closely related after all.

Superorder: Dinosauria
   Order: Theropoda
      Suborder: Megalosauria
         Superfamily: "Ceratosauroidea"
            Family: Ceratosauridae
               Subfamily: Ceratosaurinae
               Subfamily: Sarcosaurinae

info panel

Guild/Ecological niche: Medium to Giant terrestrial carnivore
Modern equivalent: none
Time: early to late link to palaeos com Jurassic period, possibly
Distribution: link to palaeos com Pangaea
Evolved from: Coelophysoidea?
Replaced: Dilophosaurs
Replaced by: Allosaurs, Abelisaurs, Tyrannosaurs
Extinction because of: Terminal Jurassic extinction event?
Descendents: ?none, ?Megalosauridae, ?Abelisauroidea
Linnean status: Family
Cladistic status: uncertain
Parent clade: Certaosauria
Adult length: less than 3 to 11.5 meters
Adult weight: 70kg to about 5 tonnes
Habitat: floodplain, uplands (but not mountain)
Diet / Preferred food: other dinosaurs, any tetrapods smaller than themselves. Some Ceratosaurs probably only preferred small animals, others went for big game.
Hunting/Food gathering/Foraging/Feeding habitat/Feeding behaviour: ambush, attacks large animals by quick slashing of the teeth, the victim dies from shock and loss of blood, small animals captured and swallowed whole
Movement: bipedal, active on land, adequate swimmers
Predators: for large species none (top of food chain)

top of page

subfamily Ceratosaurinae

sketch of skull

Ceratosaurus nasicornis Marsh, 1884b

Horizon: Morrison formation of Colorado and Utah
Age: link to palaeos com Kimmeridgian
Place: north-central link to palaeos com Pangea
Remains: remains of five individuals, including one nearly complete skeleton
Length: 5.7 to 7 meters
Weight: 500 kg to 1 tonne

Comments: Interesting because it is structurally so much more primitive than its allosaur contemporaries, this medium-sized theropod is characterised by its tall nose horn and smaller preorbital horns in front of the eyes. It also possesses a row of bony nodules down the spine, similiar to those of pseudosuchian thecodonts and the earliest dinosaurs. The skull lightly-constructed skull is armed with quite proportionally large teeth. It is unlikely this animal could bring down large game (in contrast to the Allosaurs); it probably preyed on smaller animals like ornithopods

Ceratosaurus magnicornis Madsen and Welles, 2000

Horizon: Morrison formation
Age: link to palaeos com Kimmeridgian
Place: north-east link to palaeos com Pangea
Length: about 5.7 meters
Weight: 500 kg

Comments: Quoting Tim Williams:
"C. magnicornis is differentiated from C. nasicornis by proportional differences in the skull, vertebrae, and limb bones. It appears to be a more robust species compared to C. nasicornis. The nasal horn is longer, but lower than that of C. nasicornis, and the lacrimal "horns" [in front of the eyes] are better developed.
I suspect though that future studies on Ceratosaurus may sink C. magnicornis as a junior synonym of C. is possible that the differences between C. magnicornis and C. nasicornis might be explained by intraspecific variation within a single Ceratosaurus species. Coelophysis bauri and Dilophosaurus wetherilli also show a lot of morphological variation among the specimens referred to each species."

Ceratosaurus dentisulcatus Madsen and Welles, 2000

Horizon: Morrison formation of Utah
Age: link to palaeos com Kimmeridgian
Place: north-central link to palaeos com Pangea
Length: 7 meters
Weight: about 1 tonne

Comments: A large ceratosaur. Quoting Tim Williams:
"C. dentisulcatus is the second new Ceratosaurus species named by Madsen and Welles. It appears to be more distinct from C. nasicornis than C. magnicornis is, and so can more reliably be considered a new species. It gets its species name by the distinct grooves (sulci) running down the length of the anterior teeth of the upper jaw. C. dentisulcatus also has fewer maxillary and dentary teeth, and the front of the dentary is strongly curved and upturned. There are also proportional differences in the elements of the skull (such as a lower snout) and postcranium compared to the two other North American Ceratosaurus species. The nasals and lacrimals are not preserved in C. dentisulcatus so its "horns" (assuming it had them) cannot be compared with the other two species."

?Ceratosaurus ingens (Janensch, 1920)

synonym: Megalosaurus ingens Janensch, 1920
Horizon: Tendaguru beds of Tanzania
Age: link to palaeos com Kimmeridgian
Place: south-central link to palaeos com Pangea
Remains: teeth
Length: estimated about 11.5 meters
Weight: about 5 tonnes

Comments: A huge animal, possibly a ceratosaur. All that is known are some distinctive ceratosaur teeth, but these are almost 15 cm long, the size of tyrannosaur teeth. Rowe and Gauthier (1990) argued that C. ingens and C. roechlingi lack diagnostic characters, and should best be regarded as nomina dubia (i.e. it is not possible to identify them properly). It is possible also too large to belong with Ceratosaurus, although it may be a related genus. But whatever it was, this superpreditor obviously preyed on the contemporay sauropod dinosaurs in its environment, perhaps by quick slashing bites rather the more powerful bites of an Allosaur.

top of page

Subfamily Sarcosaurinae

Little is known about this family. According to the hip characteristics, teh Sarcosaurines appears to be more advanced than Ceratosauridae, despite being much earlier in time. Sarcosaurus woodi is the only certain species. Genusaurus sisteronis Accarie, Beaudoin, Dejax, Fries, Michard, and Taquet, 1995 from the mid link to palaeos com Albian of France is also placed here. Based on a partial skeleton, this species has many primitive features. However, it lived much later than Sarcosaurus, and although the two are generally included together, I remain sceptical until more information comes to light.

Sarcosaurus woodi Andrews, 1921

Horizon: Lower Lias of Leicestershire, England
Age: link to palaeos com Sinemurian
Place: middle north- link to palaeos com Pangea (Europe)
Remains: femur, vertebrae, partial pelvis
Length: about 2.8 meters
Weight: 70 kg

Comments: Based on poor and fragmentary remains, this small theropod seems to be is very much like Ceratosaurus. The more dorsal placement of the otherwise similiar femoral outer ridges imply this may be a more advanced species than Ceratosaurus, despite the latter's much later age. There may recently have been a skull found that belongs to this animal.

top of page

Web links Links Web links

by Professor Paul Eric Olsen, part of DINOSAURS AND THE HISTORY OF LIFE - GEOLOGY V1001x

links link to palaeos com Ceratosauria - Palaeos

cladogram Ceratosauria - - Justin Tweet's Thescelosaurus! pages

Dinosauricon Neoceratosauria by T. Mike Keesey - definition of the group and list every known species. Shows Ceratosaurus related to the Abelisauria - although this is by no means certain.

Jurassic Gallery Jurassic Gallery - fantastic artwork by M. Shiraishi. By Japanese and English

cladogram Ceratosauria Mikko's phylogeny site

printed reference Gregory S. Paul, Predatory Dinosaurs of the World Simon and Schuster, 1988

printed reference Rowe, T., & Gauthier, J., 1990: Ceratosauria. 151-168 in Weishampel, D. B., Dodson, P., & Osmólska, H. (eds.), 1990: The Dinosauria, University of California Press, Berkley, Los Angeles, Oxford

Dinosaur Mail List archivesTimothy Williams, New _Ceratosaurus_ paper

Darryl Jones Re: Ceratosaurus paper

printed reference Madsen Jr., J.H. and Welles, S.P. , 2000. Ceratosaurus (Dinosauria, Theropoda), a revised osteology. Utah Geological Survey Miscellaneous Publications (MP-00-2): 80 p.

internal link cautionary note (please read before using this page as reference material!)

up one node (internal link) back to Theropoda

Dinosaur main page
main page

images not loading? | error messages? | broken links? | suggestions? | criticism?

contact me

page history

page uploaded 6 May 1999
converted to css format and additional material added 13 December 2000, links updated 16 January 2010

content and html by M.Alan Kazlev