Regaliceratops peterhewsi was discovered in 2005 by Canadian geologist Peter Hews. It was described in 2015 by two paleontologists from the Royal Tyrrell Museum; Caleb M. Brown and Donald M. Henderson.
In 2005, Peter Hews was on a fishing trip along the Oldman River in Southwestern Alberta, about 25km North of the towns of Lundbreck and Crowley. He found the skull sticking out of the rock, about a metre above the surface of the water. The skull was of interest, as it was preserved in its natural shape, not flattened like many fossil skulls.
Regaliceratops peterhewsi is a chasmosaurine ceratopsian from the triceratopsini family. It was most likely found in the St. Mary River formation, though there is a little ambiguity. Where the specimen was found, there are two formations found: the St. Mary River and Willow Creek formations. The two formations are kind of mixed, due to geologic shifting and upheaval. Along with the holotype, fossilized pollen, Scollardia trapaformis, was found and confirmed by a paleobotanist. Additionally, another chasmosaurine (Eotriceratops xerinsularis) was found in rock formations from the same age as the holotype, mostly confirming the St. Mary River formation. Ceratopsians are four-legged horned dinosaurs with beaked mouths.
The holotype consists of the skull, missing the rostral bone and the lower jaws. The holotype is thought to be about 5 metres in length, and weigh about 1.5 tonnes.
It was discovered to be a new species by its horns and frill ornamentation. The frill is similar to other chasmosaurines in size, being relatively small, but different in the fact that its "spikes" (called epiossifications) are large and considerably more elaborate. It has a long nose horn and two short horns above the eyes, which is generally what is found in centrosaurines, not chasmosaurines.
According to the fossil record previous to this discovery, ceratopsians were generally split into two main groups: chasmosaurines and centrosaurines. Chasmosaurines had small nose horns, large eye horns, and simple frills with smooth or scalloped edges. Centrosaurines had large nose horns, small eye horns, and elaborate frills with spikes or spades. This display of characteristics from both chasmosaurines and centrosaurines is so far unique, making it easy to descibe as a new species, and shows signs of convergent evolution (two separate species developing the same characteristics separately).
The discovery of Regaliceratops peterhewsi shows that ceratopsians had more diversity than previously thought, as previously discovered ceratopsians from the Maastrichtian age all showed very similar traits.
Regaliceratops peterhewsi was nicknamed "Hellboy" by its paleontologists, mostly due to the conditions they had to endure to extract the specimen. The specimen was found in a steep cliff face, close to the water. They could not let any debris fall into the river, as it was a habitat for Aberta's provincial fish (the bull trout); a challenge, with the speciment being found near the surface of the water. The paleontologists also described the rock as "evil hard rock".
As with other ceratopsians, Regaliceratops was herbivorous, as evidenced by its upper jaw and teeth.
Regaliceratops comes from the Greek "regalis" meaning "royal", and Latin "ceratops" meaning "horned face". Peterhewsi refers to Peter Hews, the geologist who discovered the specimen.