It was about 5. Although closely related to Styracosaurus, it had a very different appearance; it had only two long, straight horns on its frill, and a strange, flattened, forward-curving nasal horn that resembled a bottle opener. Although the nasal horn was probably not a very effective weapon, the straight horns in the frill probably protected the animal from the bites of large carnivorous dinosaurs, preventing them from biting the neck of the back of the frill.
Like Pachyrhinosaurus, Einiosaurus is known to have lived in large herds. Its remains have been found in Montana. Its spectacular remains were found in Utah. It had a very small nasal horn, but its brow horns were quite large, and the ones in top of the frill were even larger. These four horns, along with the forward-curving frill, gave this animal a strange appearance, different from all other horned dinosaurs known.
Diabloceratops seems to be a primitive horned dinosaur, since it shares some anatomical traits with the protoceratopsids, a closely related but less advanced family. Its jaws were massive, which suggests that its bite was very powerful. The same is true for most other ceratopsians and it is possible that many species used their huge beaks as much as their horns, as weapons against predators.
Unlike the horn of a rhinoceros, which is made entirely of keratin the same protein hair and nails are made of , Rubeosaurus, and most other ceratopsians, had horns composed of a bony core covered on a sheath of keratin. Keratin usually does not fossilize, so the horns of ceratopsians were longer and sharper in life than they look in museums and photos of the fossils. Unfortunately, without the keratin sheath, it is impossible to know exactly how long the horns were.
Another particular trait of Rubeosaurus is the straight horns on top of the frill, which coverage so that the tips almost touch each other. Although the press initially claimed that Coahuilaceratops weighed 12 tons twice as much as your average T-Rex! It was described in , being one of the latest additions to the ceratopsian bestiary, and certainly one of the most spectacular of all dinosaurs.
Fifteen if you count the epijugal bones. This is perhaps the best proof that dinosaurs took theatricality quite seriously; the forward facing horns in the frill and down-facing, curved horns on its brows were not practical for either attack of defense, and were more likely an exhibition to frighten rivals and predators and to attract potential mates.
Ceratopsian skulls, with Styracosaurus on the far left, Natural History Museum of Utah The evolutionary origins of Styracosaurus were not understood for many years because fossil evidence for early ceratopsians was sparse. The discovery of Protoceratops , in , shed light on early ceratopsid relationships,  but several decades passed before additional finds filled in more of the blanks.
Fresh discoveries in the late s and s, including Zuniceratops , the earliest known ceratopsian with brow horns, and Yinlong , the first known Jurassic ceratopsian, indicate what the ancestors of Styracosaurus may have looked like. These new discoveries have been important in illuminating the origins of horned dinosaurs in general, and suggest that the group originated during the Jurassic in Asia, with the appearance of true horned ceratopsians occurring by the beginning of the late Cretaceous in North America.
This was based on a series of fossil skulls from the Two Medicine Formation of Montana. Subtle changes can be traced in the arrangement of the horns through this lineage, leading from Rubeosaurus to Einiosaurus , to Achelousaurus and Pachyrhinosaurus. However, the lineage may not be a simple, straight line, as a pachyrhinosaur-like species has been reported from the same time and place as Styracosaurus albertensis. A bonebed composed of Styracosaurus remains is known from the Dinosaur Park Formation of Alberta, about halfway up the formation.
This bonebed is associated with different types of river deposits. They may, however, have been able to knock down taller plants with their horns, beak , and bulk. Older teeth on top were continually replaced by the teeth underneath them. Unlike hadrosaurids , which also had dental batteries, ceratopsid teeth sliced but did not grind.