One of the most unusual horned dinosaurs ever discovered, the newly identified Regaliceratops peterhewsi lived some 69 million years ago in what is now southern Alberta, Canada. Though it is clearly a relative of Triceratops, the new dinosaur—nicknamed “Hellboy” for its unusual facial horns and bony frill—shares some traits with a different group of horned dinosaurs, and represents an unexpected and exciting case of the phenomenon known as evolutionary convergence.
A decade ago, local geologist Peter Hews spotted the first bones of a previously unknown dinosaur protruding from a cliff in the Oldman River in southern Alberta, Canada. When paleontologists reassembled the complete skull, it weighed some 592 pounds. The skull resembled that of another horned dinosaur, Triceratops, but it had a taller nose horn and two relatively small horns above its eyes.
Its most distinctive feature, however, was the bony frill, a crown-like arrangement of large pentagonal plates atop its head that lent it a regal appearance. For this reason, the researchers officially named the newly identified species Regaliceratops (which means “royal horn face” in Latin) peterhewsi (in honor of the man who found the first bones). Unofficially, however, they dubbed the dinosaur “Hellboy” for its resemblance to the comic book—and movie—character of that name.
In a study published this week in the journal Current Biology, paleontologists Caleb M. Brown and Donald Henderson of Canada’s Royal Tyrell Museum described the skull of Regaliceratops peterhewsi in detail, and explain how its features distinguish it from other known horned dinosaurs. The researchers believe that “Hellboy” was similar in size to today’s largest rhinoceroses: about 16 feet (5 meters) long and 5 feet (1.5 meters) tall at the hips, and weighing about 1.5 tons. Like other horned dinosaurs, it probably emerged during the Late Cretaceous, between 65 million and 100 million years ago. While the sharp horns above the nose were most likely used for defense against predators, including Tyrannosaurus rex, the paleontologists believe the large bony frill was probably ornamental, used to indicate health and sexual prowess.
Scientists have classified horned dinosaurs into two groups: Chasmosaurines (which include Triceratops) and Centrosaurines. The newly identified species shares traits with both groups: Though it is clearly a relative of Triceratops, the horns and frill arrangement more closely resembles that of Centrosaurus, which scientists believe had gone extinct by the time Regaliceratops emerged. For that reason, the researchers believe that Regaliceratops evolved from one lineage while at the same time developing traits from another one—an intriguing process known as independent evolutionary invention, or convergent evolution.
For many scientists, the identification of such an unusual new horned dinosaur raises the exciting possibility that there may be more unidentified dinosaur species out there waiting to be discovered. As James Farlow, geology professor at Indiana University-Purdue University Fort Wayne told Smithsonian: “This discovery shows that we are perhaps still quite a ways from knowing the complete diversity of dinosaur species in the Late Cretaceous of western North America.”