Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder:Theropoda
Family:†Ceratosauridae
Genus:†Ceratosaurus
Marsh, 1884

Ceratosaurus followed the bauplan typical for large theropod dinosaurs. A biped, it moved on powerful hind legs, while its arms were reduced in size. The holotype specimen was an individual about 5.3 metres (17 ft) long; it is not clear whether this animal was fully grown.Marsh (1884) suggested that the holotype individual weighed about half as much as Allosaurus. In more recent accounts, it was estimated at 418 kilograms (922 lb), 524 kilograms (1,155 lb) and 670 kilograms (1,480 lb) by separate authors. Two skeletons, assigned to the new species C. magnicornisand C. dentisulcatus by James H. Madsen and Samuel P. Welles in a 2000 monograph, were substantially larger then the holotype. The larger of these, C. dentisuclatus, was informally estimated by Madsen to have been around 8.8 metres (29 ft) long. American science writer Gregory S. Paul, in 1988, estimated the C. dentisulcatus specimen at 980 kilograms (2,160 lb). A considerably lower figure, 275 kilograms (606 lb) for C. magnicornis and 452 kilograms (996 lb) for C. dentisulcatus, was proposed by John Foster in 2007.

Ceratosaurus has been found in the Morrison Formation of Utah, Colorado, Wyoming, and Oklahoma. One of the more complete skeletons of Ceratosaurus is housed at the NHMU. This specimen was found at the Cleveland-Lloyd Dinosaur Quarry. Ceratosaurus is distinctive for its horn-like crests. Uniquely among theropods, Ceratosaurus possessed a row of small, elongated and irregularly formed osteoderms (skin bones) running down the middle of its neck, back and most of its tail. Apart from the body midline, the skin contained additional osteoderms, as indicated by a 6 × 7 cm large plate found together with the holotype specimen; the position of this plate on the body is unknown

Ceratosaurus is a mid sized predator occupying a lower end of the island food web. It’s heavier than Dilophosaurus and Utahraptor but much lighter than Albertosaurus or Allosaurus. They use their size and maneuverability to help them live their deep forest lives. They are secretive predators seldom seen in the open. The forest is their advantage to keep safe from carnivores like Carnotaurus and Albertosaurus who use their speed and open ground to chase and tire down prey. Ceratosaurus has been seen to be almost a scavenger bully at times. Sizing up and chasing off smaller predators away from their kills. Utahraptors and Dilophosaurus simply don’t have the bulk to stand up to this robust predator.

They usually are seen living in the territory of a larger carnivore. Stalking their kills and while the larger predator is off patrolling Ceratosaurs will go on feast on the food they’ve left behind. They are much smaller than the largest predators on the island and have to use their brains over brawn. Having a large brain to mass ratio they are one of the smarter animals on the island. They’ve been observed solving complex puzzles to get their food and have been documented mimicking lower pitched dinosaur calls to warn off smaller predators from kills. On one occasion it worked on an Acrocanthosaurs that mistook a Ceratosaurus’ mimic for a Tyrannosaur and fled the scene of it’s kill.

Hunting and Diet
Ceratosaurus finds the main components of its diet in smaller animals, much of which are other less powerful theropods, including ; Herrerasaurus, Austroraptor, Utahraptor and Rugops One bite from this dinosaur can easily disable smaller predators and they will often choose carnivore flesh over herbivores.
They have been also seen using their superior maneuverability to hunt prey sometimes inaccessible to other predators. Larger herbivores like diabloceratops and sub adult stegosaurus are also seen baring injuries that match the bite marks from ceratosaurus. They will try and target the head and neck of Stegosaurus, this is always a job for a well coordinated pair. One distracts the herbivore to expose its tail in defense while the other goes in to attempt to make a kill. More often than not hunts are failed and these carnivores are found scavenging on their own species.

Interspecific competition
Ceratosaurus being a mid sized carnivore tries to stay unnoticed and keep away from larger carnivores on the island. And speaking of larger carnivores, the bad blood that’s commonly thought about when mentioning Allosaurus and Ceratosaurus has not disappeared since the jurassic period though. Ceratosaurus has been known to attack weak Allosaurs in hopes of a meal. Sometimes this goes well, other times this three horned predator bites off more than it can chew. Most of the time Ceratosaurus will avoid an Allosaurus though, using brains over brawn and trying their best not to go toe to toe with the predator that’s twice their size. Ceratosaurus being as lightweight as it is compared to other predators will shy away from many larger carnivores. They give larger predators like Albertosaurus, Acrocanthosaurus and Suchomimus a wide berth, not wanting to be seen and preferring to operate undetected.

They are commonly seen as solitary predators, but are also known to pair up together as hunting partners. These hunting pairs may or may not mate, and every so often they can break up and rejoin with a new partner at a different time. This being said they are highly aggressive to other ceratosaurus not in their pair and will vocally chase them away. Unless the pair does not have food, in that case they will silently hunt and bring down another ceratosaurus if given the chance. They are also highly aggressive to other carnivores their own size. Dilophosaurus, Utahraptors and Rugops are all on the Ceratosaurus’ list.


Male Ceratosaurs are loud when it comes to fight for breeding rights. Males will search for females, if a lone male ceratosaurus finds a pair he will start broadcasting his presence to be known to the other male. They will lower their heads and show off their crest size and color to each other in turns. Then they will circle each other and flush blood towards their heads to show off who is more colorful and healthy. If one male isn’t intimidated by this display they will often charge each other. A mock charge is sometimes employed to try and scare off his opponent but usually this is taken as a direct threat and the pair of males will fight. Often times this fight ends in death of one or both of the males, hopefully one will back down early on and will leave a safe distance away. Once the lost male has moved three to four body lengths away from the victor he will heal his immediate wounds and then leave.

Females are quieter and once they have mated they make a nest and lay their eggs. She constantly checks on her eggs making sure they are safe and will press her snout against the nest to try and estimate a temperature. Too hot she will use her massive foot claws and carefully dig out a few layers of dirt. Too cold and she’ll pile on more layers. Any animal that approaches her nest is an unlucky one, as long as she can handle it. Anything her size and smaller will be warded off by her charges and attacks. And the male is often times lying in ambush waiting for another animal to try and steal the eggs. If for example a dilophosaurus tries to outflank the female and go for her eggs the male will rush out of cover and dispatch the attacking predator. The parents take turns feeding, drinking water and watching the eggs and or newborn chicks.

Their offspring go through very drastic changes from birth to adulthood. Having little nubs instead of crests at birth they will develop their namesake horns in their youth. The offspring, while having a lack of large horns have been documented rutting and slowly squaring off and much like a triceratops, pressing their heads against each other until one relents. This is not something they carry into adulthood, but maybe something carried genetically from a previous lifetime, where their ancestors had different purposes for smaller less delicate horns. Once the chicks become subadults they will be viewed as food by the parents and promptly chased off and warned away. The next time they will meet their mother and father it might be in a fight for who becomes the next meal.