Ceratosaurus

Ceratosaurus was a Horned Jurassic Predatory Theropod

Ceratosaurus (pronounced sayr-AT-oh-sawr-us) means “horned lizard”. It’s from the Greek keratos, meaning “horn”, and sauros meaning “lizard”. It was a fearful predator that lived during the late Jurassic period, about 150 million years ago, with a huge tail, strong and stocky body, and heavy bones. The biggest rival of Allosaurus, another carnivorous theropod, they were similar in appearance except for an extra toe on each of Ceratosaurus’ legs. They were also both scavengers and predatory whenever the opportunity presented itself.

Quick Facts

What did Ceratosaurus look like?

Ceratosaurus was a Bipedal Theropod with a Horned Nose

Ceratosaurus was bipedal with a large tail and head, both unusually disproportionate to a typical theropod’s body. It had a. prominent horn on its nose that came from protruding nasal bones and hornlike ridges in front of its eyes, like allosaurus, from protruding facial bones.It also had a large jaw with knife-like teeth and strong but short forelimbs. Ceratosaurus was distantly related to birds among theropods, but the fossil evidence still shows bird-like features including a more avian-esque ankle joint than Allosaurus. Also, it’s skeletal structure was fused in a way that we see a lot in modern day birds.

Physical Attributes of Ceratosaurus

The exact length of Ceratosaurus is still under debate. Estimations range from 15 to a little over 20 feet. There have been different specimens found at different times that varied in length by several feet. One smaller specimen may have been not quite fully grown. It was found to be 18 feet and one British Paleontologist, David B. Norman, estimated that the Ceratosaurus could reach a maximum length of 20 feet, although another specimen was thought to be part of a 22 foot long, or more, Ceratosaurus assuming the same proportions as other known specimen at the time.

Relative to the wide-ranging lengths of Ceratosaurus, the verdict is also out as to how heavy it was. The 18 foot specimen was estimated to be half a ton and the 22 foot specimen estimated to be a full ton.

A very low estimate for weight was developed by John Foster in 2007. He estimated mass from femur length which resulted in a figure of 606 lb for one specimen and 996 lb for the larger specimen.

What was the Point of the Nasal Horn?

There is some speculation among paleontologists about whether the nasal horn on the Ceratosaurus was functional. 100 years ago, it was considered by a couple prominent paleontologists to be a powerful weapon. But that interpretation is no longer considered plausible. In 1985, Norman theorized the horn might have, instead, been for male ceratosaurs fighting amongst each other for breeding rights.

A theory that was proposed by two other paleontologists a few years later expressed that it was probably for display only and served no combative purposes.

What did Ceratosaurus eat?

Ceratosaurus was a Carnivore, Comfortable on both Land and Water

The paleontologist Othniel Charles Marsh, who named him in 1884, first observed that Ceratosaurus had a physique very similar to crocodiles, with its long thin crocodile-like tail and flexible body, and was probably a good swimmer. Recent research provides more evidence backing Marsh up and suggests that Ceratosaurus often preyed on aquatic animals like fish and crocodiles. It also was capable of hunting large animals like sauropods and could have been a pack hunter. It’s main rival was Allosaurus. They both are known to have eaten sauropods, stegosaurus, dryosaurus, and iguanadonts. Scavenging on corpses was also common. Ceratosaurus took the opportunity to eat from anywhere it could.

History and Discovery of Ceratosaurus

Ceratosaurus is a rare fossil to find, but one reliable source has been the Cleveland Lloyd Dinosaur Quarry in Utah. The dinosaur quarry is rich in fossils, many belonging to predators that are even rarer than the Ceratosaurus. Paleontologist O.C. Marsh first described the type species Ceratosaurus nasicornis in 1884, making a restoration of it a few years later in his 1896 book “The Dinosaurs of North America”. Several more type species have been described since then. Two of the type species were described by paleontologists James Masden and Samuel Welles in 2000 in a detailed monotgraph. One was found in the Fruita Paleontological Area in Colorado and named Ceratosaurus magnicornis. The other was found in the Cleveland-Lloyd dinosaur quarry and called Ceratosaurus dentisulcatus.

The Ceratosaurus dentisulcatis was unique in several ways. Unlike the first type species, this one took Madsen and Welles many years to put the skeleton together from scattered fossils. Secondly, when the parts were viewed as a whole, they were amazed by the size of this Ceratosaurus. It was much bigger than any that had been discovered before. Lastly, the Ceratosaurus dentisulcatus was different from other species anatomically. It had larger teeth that curved inward and a lower set nasal opening, but the horned features were not preserved, so it is unknown how that aspect of it’s skull was different.

Significance of Ceratosaurus in History

Ceratosaurus has been a popular dinosaur in the media, especially in movies, including D.W. Griffith’s Brute Force in 1914. It was the first live action movie to ever feature dinosaurs. Considering Ceratosaurus fossils are so rare, in combination with it’s long film career, it is possible that the dinosaur has been seen more in film than in fossil-form. But, hopefully, that will change. As paleontologists increase the known fossil inventory for Ceratosaurus, our understanding of the real Ceratosaurus will increase as well.