Photo of display at the Museum of Ancient Life, Lehi, Utah. The dinosaur park features a different cast of the same skeleton.
Weird and wonderful, Ceratosaurus has perplexed paleontologists and pleased popular perceptions for 136 years. It also abets awful alliteration, apparently.
The full scientific name of this animal translates roughly to “horn lizard with a horn on its nose,” which might explain its unusual ability to induce linguistic awkwardness in science writers.
Though we usually call them horns, Ceratosaurus’ headgear didn’t have the right shape to perform the same job as, say, a cow’s horns. “Crests” might be more accurate, but naming the animal “Crestosaurus” would doom it to the lowly cultural function of toothpaste mascot. In the past, scientists have hypothesized a defensive function for them, but their thin cross-section made them too fragile to endure any significant impact.
Hailing from the Morrison formation of Western North America—the formation that has made Utah’s Dinosaurland so famous—Ceratosaurus formed part of a triumvirate of large dinosaurian carnivores of Utah’s Jurassic. It didn’t seem to reach the same size as Allosaurus and Torvosaurus though, which may explain its bizarre headgear. After all, would you want to fight something that looked that nasty? If those horns indeed served as tools of intimidation, whether against rivals of the same species or against the larger carnivores of the region, Ceratosaurus
may have had a bit of a poser attitude to go along with it—when surprised, it may have bellowed and waved its head to chase interlopers off or buy time for a tactical withdrawal. Behavioral hypotheses like this, however, usually prove impossible to test, so take that with a whopping grain of salt.
Even if Ceratosaurus didn’t use its horns like modern punks use their neon green mohawks, it seems to have needed a little extra armor plating as a possible backup plan. Rows of osteoderms, or bone-hard scales like those found on crocodiles, lined its back. They would have given the animal a rougher appearance, not to mention they might have discouraged bites from rivals of any species.
Though most scientists only consider the species nasicornis valid, some authorities also count two other species: dentisulcatus and magnicornis. Both species were founded on some pretty scrappy remains in the year 2000 by the illustrious Utah-based paleontologist Jim Madsen. Time will tell if these species gain greater acceptance, but based on what we know now, most paleontologists consider their differences well within the scope of individual variation. Scientists have also found fragmentary remains along with other animals that resemble those of the Morrison formation, like the Brachiosaur’s African cousin Giraffatitan, in the Tendaguru formation of Tanzania. Unfortunately, their poor condition does not allow positive identification at this time.
This genus of dinosaurs seems to have roamed across much of Laurasia (that is, the northern hemisphere), and its close relatives may have ranged even farther. Genyodectes, from Argentina, may have been a ceratosaur, and other possible cousins have been reported from China and Australia. Even so, the only really good specimens come from the Morrison formation, so the group remains fairly mysterious. Their descendants (or cousins) include a Cretaceous group called the Abelisaurs which is also known for some horned members, like Carnotaurus.
Ceratosaurus may not enjoy the same celebrity as some of its cousins, but Hollywood has at least offered it cameos in films ranging from Brute Force (one of the first bad B-movies in sci-fi cinema) to Fantasia to its most recent appearance in Jurassic Park III. The famous paleontologist Robert Bakker considers it his favorite dinosaur.
Paul, G. S. (1988). Predatory Dinosaurs of the World: a Complete Illustrated Guide. Simon & Schuster. Page 278.
Carpenter, K. (Ed.). (2005). The Carnivorous Dinosaurs. Indiana University Press. Pages 288-9. (NOTE: Though the text says that signaling structures are less plausible than weapon functions, the context makes it clear that this is a typo and the intent is that they are more plausible than weapon functions.)
Gilmore, Charles W. 1920. "Osteology of the carnivorous Dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) and Ceratosaurus." Bulletin of the United States National Museum. i–xi, 1-159, 79 figs, 36 pls. Page 113.
Madsen, J. H., Jr., and S. P. Welles. 2000. Ceratosaurus (Dinosauria, Theropoda) a revised osteology. Utah Geological Survey Miscellaneous Publication 00-2:1-80.