page_title: Styracosaurus
section_title: Horns and frill
hierarchical_section_title: Styracosaurus / Paleobiology / Horns and frill
caption_attribution_description: Reconstructed line drawings of the complete or relatively complete parietals of the centrosaurine ceratopsid Styracosaurus albertensis in dorsal (i.e., orthogonal to frill). Specimens are arranged in approximate order of increasing size of parietal ornamentation and size. A, TMP 2009.080.0001. B, TMP 1989.098.0001. C, TMP 1989.126.0001. D, TMP 1988.036.0020. E, CMN 344. F, TMP 2005.012.0058. G, TMP 1987.052.0001. H, UALVP 55900. I, ROM 1436. Based on development of the parietal ornamentation A−C represent subadult specimens, whereas D−I are regarded as largely skeletally mature. Scale bar = 50 cm.
context_page_description: Styracosaurus is a genus of herbivorous ceratopsian dinosaur from the Cretaceous Period, about 75.5 to 75 million years ago. It had four to six long parietal spikes extending from its neck frill, a smaller jugal horn on each of its cheeks, and a single horn protruding from its nose, which may have been up to 60 centimetres long and 15 centimetres wide. The function or functions of the horns and frills have been debated for many years.
  Styracosaurus was a relatively large dinosaur, reaching lengths of 5.5 metres and weighing nearly 3 tonnes. It stood about 1.8 meters tall. Styracosaurus possessed four short legs and a bulky body. Its tail was rather short. The skull had a beak and shearing cheek teeth arranged in continuous dental batteries, suggesting that the animal sliced up plants. Like other ceratopsians, this dinosaur may have been a herd animal, travelling in large groups, as suggested by bonebeds.
  Named by Lawrence Lambe in 1913, Styracosaurus is a member of the Centrosaurinae. One species, S. albertensis, is currently assigned to Styracosaurus.
context_section_description: The large nasal horns and frills of Styracosaurus are among the most distinctive facial adornments of all dinosaurs. Their function has been the subject of debate since the first horned dinosaurs were discovered.
  Early in the 20th century, paleontologist R. S. Lull proposed that the frills of ceratopsian dinosaurs acted as anchor points for their jaw muscles. He later noted that for Styracosaurus, the spikes would have given it a formidable appearance. In 1996, Dodson supported the idea of muscle attachments in part and created detailed diagrams of possible muscle attachments in the frills of Styracosaurus and Chasmosaurus, but did not subscribe to the idea that they completely filled in the fenestrae. C.A. Forster, however, found no evidence of large muscle attachments on the frill bones.
  It was long believed that ceratopsians like Styracosaurus used their frills and horns in defence against the large predatory dinosaurs of the time. Although pitting, holes, lesions, and other damage on ceratopsid skulls are often attributed to horn damage in combat, a 2006 study found no evidence for horn thrust injuries causing these forms of damage (for example, there is no evidence of infection or healing). Instead, non-pathological bone resorption, or unknown bone diseases, are suggested as causes.
  However, a newer study compared incidence rates of skull lesions in Triceratops and Centrosaurus and showed that these were consistent with Triceratops using its horns in combat and the frill being adapted as a protective structure, while lower pathology rates in Centrosaurus may indicate visual rather than physical use of cranial ornamentation, or a form of combat focused on the body rather than the head; as Centrosaurus was more closely related to Styracosaurus and both genera had long nasal horns, the results for this genus would be more applicable for Styracosaurus. The researchers also concluded that the damage found on the specimens in the study was often too localized to be caused by bone disease.
  The large frill on Styracosaurus and related genera also may have helped to increase body area to regulate body temperature, like the ears of the modern elephant. A similar theory has been proposed regarding the plates of Stegosaurus, although this use alone would not account for the bizarre and extravagant variation seen in different members of the Ceratopsidae. This observation is highly suggestive of what is now believed to be the primary function, display.
  The theory of frill use in sexual display was first proposed in 1961 by Davitashvili. This theory has gained increasing acceptance. Evidence that visual display was important, either in courtship or in other social behavior, can be seen in the fact that horned dinosaurs differ markedly in their adornments, making each species highly distinctive. Also, modern living creatures with such displays of horns and adornments use them in similar behavior.
  The use of the exaggerated structures in dinosaurs as species identification has been questioned, as no such function exists in vast majority of modern species of tetrapods (terrestrial vertebrates).
  A skull discovered in 2015 from a Styracosaurus indicates that individual variation was likely commonplace in the genus. The asymmetrical nature of the horns in the specimen has been compared to deer, which often have asymmetrical antlers in various individuals. The study carried out may also indicate that the genus Rubeosaurus may be synonymous with Styracosaurus as a result.
caption: Variation in frill morphology; the top row are subadults, the rest are mature
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