An Ultimate Guide to Ceratosaurus: The Horned Lizard

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Name Meaning“Horn Lizard”Height2 meters (6.5 feet)
PronunciationKeh-RAT-oh-sore-usLength6 to 7 meters (19 to 22 feet)
EraMesozoicLate JurassicWeight0.6 to 2 tons (1,200 to 4,000 lbs)
ClassificationDinosauria,‭ Saurischia & TheropodaLocationNorth America, Europe, and Africa

Ceratosaurus Pictures

Ceratosaurus dinosaur roaring isolated in white background - 3D render
Ceratosaurus roaring | Elenarts108 via GettyImages

The Ceratosaurus

Gage Beasley Prehistoric's Ceratosaurus Concept
Gage Beasley Prehistoric’s Ceratosaurus Concept

Ceratosaurus is a genus of theropod that lived during the Late Jurassic period, dating from the Kimmeridgian to the Tithonian ages. 

While North America is where Ceratosaurus was originally discovered, fossils have been found in several parts of the world, suggesting they had a larger range than first believed.

Ceratosaurus was only a medium-sized theropod but was one of the larger carnivores during the Jurassic period. 

Discovered in the late 1800s, the first specimen of Ceratosaurus was nearly complete and was the foundation for the creation of the Ceratosauridae family. 

Ceratosaurus was not like other carnivorous theropods, as it had a prominent horn on the tip of its nose. 

Horns on predators are not common since this is typically a defensive trait. 

Ceratosaurus | Elenarts108 via GettyImages

Ceratosuarus showed dinosaurs evolved to have various traits and helped paleontologists understand the types of dinosaurs that lived during the Jurassic period. 

This article will cover everything you’d want to know about Ceratosaurus, including things like their diet, habitat, and how they fit into their prehistoric ecosystem. 

Finding such a well-preserved fossil of Ceratosaurus has allowed paleontologists to better understand various types of theropods and their evolution. 

Gage Beasley's Prehistoric Shirt Collection
Gage Beasley’s Prehistoric Shirt Collection
Gage Beasley's Prehistoric Plush Collection
Gage Beasley’s Prehistoric Plush Collection

Physical Characteristics

Ceratosaurus was a medium-sized theropod and had similar traits to their relatives, like their bipedal walk, short arms, and large heads. 

The Ceratosaurus had a length ranging between 5.3 to 7 meters (17 to 23 ft). 

Gage Beasley Prehistoric's Ceratosaurus Concept
Gage Beasley Prehistoric’s Ceratosaurus Size Comparison Chart

There have been several specimens of Ceratosaurus discovered, and their maximum weight is estimated at 600 kgs (1,320 lbs).

The skull of Ceratosaurus was large and had a length of around 60 cm (24 in.) and a width of 16 cm (6.3 in). 

On the nose of this dinosaur was a bony growth. 

The skull fossil of this dinosaur has a bony horn core, which had a length of 13 cm (5.1 in) and a width of 2 cm (0.79 in.) at its base. 

Ceratosaurus surveys the water
Ceratosaurus surveys the water | Elenarts108 via GettyImages

When alive, the bone of Ceratosaurus would have been larger than on its fossil, as it would be supported with keratin.

Ceratosaurus is called the “horned lizard” since they not only had a row of horns on their head but also horns running along their spine. 

The eyes of these dinosaurs had prominent ridges, similar to Allosaurids. 

Along with the armored scales that covered Ceratosaurus, they had large teeth with sharp claws to help defend themselves. 

Habitat and Distribution

Ceratosaurus lived in the Jurassic period and managed to survive into the Cretaceous period. 

These dinosaurs lived in North America and have been found in formations dating to the late Oxfordian, Kimmeridgian, and Tithonian stages of the Jurrasic period. 

The full range of Ceratosaurus likely included modern Africa, Europe, and North America.

The majority of Ceratosaurus fossils have been found in North America, but there have also been reports of this dinosaur being discovered in Tanzania, Switzerland, and Uruguay. 

While their range seems much larger than originally thought, further studies are needed to describe and confirm the fossils discovered.

Morrison Formation
The distinctive banding of the Morrison Formation | Michael Overton via Wikipedia (CC BY-SA 2.5)

Places where Ceratosaurus was found, like the Morrison Formation, have been studied in-depth and give a bit of insight into the habitats these dinosaurs lived in. 

The Morrison Formation region had periods of dryness but was mostly moist and humid in the Jurrasic period.

Habitats like swamps, lowlands, and woodlands next to streams and rivers are where this species lives. 

Ceratosaurus lived in North America before even the rocky mountains and lived in habitats with lots of fast, moving rivers. 

Behavior and Diet

A carnivorous theropod Ceratosaurus dinosaur hunts a smaller Juravenator | CoreyFord via GettyImages

The main food source for Ceratosaurus was herbivorous dinosaurs that they co-existed with. 

Ceratosaurus was a carnivore and hunted its prey. 

They had large sharp teeth that were curved and had serrated edges to help them bite through thick flesh. 

The teeth of Ceratosaurus measured a bit over 22 cm (9 inches) in length.

Their upper jaw had the longest teeth that would almost stick out of their mouth. 

Distinguishing Skull Features of Ceratosaurus | Jens Lallensack via Wikipedia (CC BY-SA 4.0)

Stegosaurus and large sauropods could have been the dinosaurs that they preyed on.

Some scientists suggest that while Ceratosaurus ate other dinosaurs, they could have also eaten other aquatic animals like fish, crocodiles, and turtles. 

Since they lived in habitats that had lots of quick freshwater, this could have been possible.

Life Cycle

Partial juvenile specimen (front parts), North American Museum of Ancient Life | Jens Lallensack via Wikipedia (CC BY-SA 4.0)

The life cycle of Ceratosaurus is relatively unknown. 

What is known is that these dinosaurs started out in eggs

During the egg and youth stage, these dinosaurs were very vulnerable and would have been preyed on by larger dinosaurs when young. 

There have been juvenile Ceratosaurus discovered, which look similar to adults but are smaller.

It is uncommon for carnivorous theropods to hunt in groups, so Ceratosaurus likely stayed with their young until they learned how to hunt and fend for themselves. 

The lifespan of Ceratosaurus is unknown, but early deaths were likely common due to the number of threats in the Jurassic period. 

Evolution and History

C. nasicornis skeleton restoration by Othniel Charles Marsh from 1896 | Photo via O. C. Marsh’s book, The Dinosaurs of North America

The first Ceratosaurus fossil was discovered by a farmer, Marshall Parker Felch, in the year 1883.

Holotype USNM 4735 is what was found and was a nearly complete specimen.

Ceratosaurus was found in the Morrison Formation, in the Garden Park region, just north of Canon City. 

After its discovery, the fossils were sent to the Peabody Museum of Natural History and described in 1884. 

Ceratosaurus nasicornis is the type species, but other species that have been named include C. dentisulcatus, and C. mangicornis

It is still up for debate whether the other species are valid or just a synonym for a younger version of the type species. 

It is the only one in its family that is believed to have a horn. 

Their horn could have been used to hunt prey or defend themselves from other dinosaurs. 

It is also possible the horn could have evolved to be used for sexual display when breeding.

Cast of the skull of the C. nasicornis holotype, showing the large nasal horn, American Museum of Natural History | Daderot via Wikipedia (CC0)

Due to how well preserved the fossil of Ceratosaurus was, scientists were able to produce a cast of the dinosaur’s brain cavity. 

Studies showed this dinosaur had a medium-sized brain, which was larger than herbivorous dinosaurs at the time

Ceratosaurus likely went extinct since it was not capable of keeping up with the evolution of other theropods, like Tyrannosaurids, but more research is needed. 

Interactions with Other Species

Two Diplodocus dinosaurs bellow in alarm as a theropod Ceratosaurus tries to sneak up behind them | CoreyFord via GettyImages

Ceratosaurus shared its habitat with a variety of dinosaur species, including other large theropods. 

During the Late Jurassic period, mammals, crocodiles, turtles, and pterosaurs began to evolve and diversify. 

The Jurassic period brought the perfect conditions for fossilization, and there have been several dinosaurs found in the same region and dated to the time period of Ceratosaurus

Some of the dinosaurs that lived alongside Ceratosaurus include:

  • Allosaurus
  • Barosaurus
  • Nanosaurus
  • Ornitholestes
  • Stegosaurus
  • Suuwassea
  • Diplodocus
  • Uteaodon
  • Gargoyleosaurus
Reconstructed skeletons of Allosaurus and C. nasicornis in fighting postures, at Dinoworld Expo, Yokohama | ★Kumiko★ via Flickr (CC BY-SA 2.0)

Ceratosaurus preyed on herbivorous dinosaurs like the Stegosaurus and Barosaurus

While large enough to take out adults, Ceratosaurus would have targeted younger dinosaurs to have a more successful hunt. 

Other larger theropods like Allosaurus competed with them for food and were likely a more dominant predator than the Ceratosaurus

Some experts believed that the large, sharp upper teeth of the Ceratosaurus suggested they had a switch in diet, and started to feed mostly on aquatic life like fish. 

Their switch in diet from herbivores dinosaurs to smaller prey could be explained by them being out-competed by larger theropods. 

Since Ceratosaurus was only medium-sized, it would have been difficult for them to kill and hunt alongside larger, more evolved dinosaurs. 

While not an apex predator, it was a fierce dinosaur that preyed on small and medium-sized animals of its time. 

Cultural Significance

Juvenile skull in multiple views | Carpenter, Kenneth via Wikipedia (CC BY-SA 4.0)

Ceratosaurus was an important discovery, as it helped paleontologists have a better understanding of the Late Jurassic Period in North America. 

Dinosaurs from the Jurassic period have been abundant, as the time period created the right conditions for fossilization to occur. 

The Morrison Formation held a nearly complete skeleton of Ceratosaurus, which was the basis for the creation of the Ceratosauridae family.

While large theropods have been heavily studied, medium-sized dinosaurs played a different role in their environment. 

By comparing Allosaurus with Ceratosaurus, scientists have been able to pinpoint the differences in what size contributes to evolution traits. 

They likely evolved to be scavengers and survived by preying on food that larger theropods would not typically go after. 

Cast of Ceratosaurus from the Cleveland Lloyd Quarry, Utah, on display at the Natural History Museum of Utah, Salt Lake City | Jens Lallensack via Wikipedia (CC BY-SA 4.0)

Having such well-preserved fossils, scientists have been able to analyze parts of Ceratosaurus that would not be possible in other, less complete specimens. 

Ceratosaurus fossils have also been helpful in figuring out how similar species looked.

Art depictions of Ceratosaurus may vary, but their unique horns and large build make them the favorite dinosaur of many. 

This dinosaur has had a big impact on paleontology and allowed scientists to have a more in-depth look at the theropods that lived millions of years ago. 


Ceratosaurus was a medium-sized theropod that lived in the late Jurassic period and is believed to have gone extinct at the start of the Cretaceous period. 

The first discovered Ceratosaurus was a well-preserved specimen and was the bases for the creation of the Ceratosauridae dinosaur family.

Since their discovery in the late 1800s, there have been a few more specimens found, some outside of North America. 

Findings of Ceratosaurus helped paleontologists understand the ecosystem during the Jurrasic into the Cretaceous period.

What is known about dinosaurs is always changing, as new fossils can change the entire landscape of what is known. 

It can take years for discovered fossils to be described and even longer for scientists to come to a consensus on an idea. 

Debates are healthy in paleontology, as it allows scientists to fully look at all aspects of discovered dinosaurs. 

Ceratosaurus was an important species in understanding Ceratosauridaes and how many theropods evolved differently. 

With more studies and discoveries in the future, what is accepted scientifically about this dinosaur may change. 


How did Ceratosaurus go extinct?

It is not known exactly how Ceratosaurus went extinct, but there have been no fossils discovered dating more than 148 million years old. 

This means they likely went extinct near the end of the Jurassic period, along with a large amount of other dinosaurs. 

A loss of a reliable food source and the inability to compete with more evolved theropods are the possible theories as to why this dinosaur went extinct. 

Did Ceratosaurus have any predators?

Ceratosaurus, while a large and fearsome predator, also shared their habitat with other larger theropods. 

They were not apex predators and could have been preyed on by dinosaurs like Allosaurus and Torvosaurus

Larger carnivorous dinosaurs would have preyed on this dinosaur when young or if they had managed to catch them off guard. 

How fast was Ceratosaurus

While dinosaurs are extinct, scientists are able to estimate their speed based on their skeleton structure and size. 

It is estimated Ceratosaurus could have had a speed ranging between 32 to 48 kph (20 to 30 mph). 

Their strong medium-sized build, sharp teeth, and speed would have made them adept hunters and capable of taking out most larger herbivores. 


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