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This New Dinosaur Is Like Triceratops with a Massive Kickass Crown

But beyond the pure wow factor, the find also represents the first example of convergent evolution ever observed in a horned dinosaur.
Regaliceratops peterhewsi skull. Photo Courtesy of Royal Tyrrell Museum, Drumheller, Alberta. Photo by Sue Sabrowski

Paleontologists based out of Alberta's Royal Tyrrell Museum have discovered the remains of a bizarre new genus of horned dinosaur, similar to the iconic herbivore Triceratops. Dubbed Regaliceratops peterhewsi on account of its regal, crown-like frill, the animal is an unusual evolutionary mashup of two prominent ceratopsid families.

Its odd mix of features has apparently earned the animal the nickname "Hellboy." But beyond the pure wow factor, the find also represents the first example of convergent evolution—the independent evolution of similar traits across families—ever observed in a horned dinosaur.

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To put it in topical Game of Thrones terms, R. peterhewsi is descended from House Chasmosaurinae, but bears head ornaments similar to House Centrosaurinae. Where the former is usually distinguished by small nose horns and simple frills, the new species broke the mould by evolving a frill lined with ostentatious pentagonal spikes and large nasal horn—traits usually associated with centrosaurines.

Regaliceratops in all its glory. Art by Julius T. Csotonyi. Courtesy of Royal Tyrrell Museum, Drumheller, Alberta

"This new species is important, because up until now, all chasmosaurines from the Maastrichtian, the latest stage of the Cretaceous, had very similar body plans," paleontologist Caleb Brown told me. Brown is the lead author of a detailed study about the skull, published today in Current Biology.

"This new species was completely unexpected and shows that the horns and frills were much more variable than previously thought," he said. "It also means that there are likely a lot more unexpected species to be discovered."

Indeed, the discovery is also exceptional because it was found in a cliffside adjacent to the Oldman River in southern Alberta, an area that has never produced ceratopsid fossils before. Perhaps Regaliceratops occupied a different niche to its chasmosaurine brethren in other parts of Alberta, which pushed it to evolve centrosaurine features. But until more specimens from the genus are discovered, it will be hard to make any firm conclusions about the dinosaur's overall behavior.

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"Researchers have noticed that distantly related species of mammal with similar horns or antlers often also have similar general social behaviours," Brown said. "Because of this, Regaliceratops peterhewsi may have had some behaviours more similar to the Centrosaurinae, but at this point, it is just speculative."

"We do know that many of the centrosaurines lived in herds because we find them in mass-death assemblages called bonebeds," he continued. "Other horned dinosaurs, like Triceratops, may have lived more solitary [lives]. In this case we only have one specimen, so we can't really say either way."

The function of these impressive cranial features, however, is on firmer speculative ground.

"When horned dinosaurs were first found, it was suggested that the horns and frill we used mainly for defence," Brown said, adding that "we have all seen illustrations of Triceratops doing battle with Tyrannosaurus."

But as paleontologists have steadily added to the collection of known ceratopsid species, the notion that these intimidating head ornaments were primarily used as defensive weapons has lost favor.

Another view of Regaliceratops. Credit: Art by Julius T. Csotonyi. Courtesy of Royal Tyrrell Museum, Drumheller, Alberta

"The best supported idea at the moment is that these structures functioned in display or signalling," Brown told me. "Basically, they were billboards, much like horns and antlers in mammals today. We think this is the case because many of these features would function poorly as armour, and the major differences between most of the species are small details in how the frill looks."

Then again, that doesn't completely rule out the notion that horned dinosaurs could do some damage in extreme circumstances. "The horns also probably had more than one function," said Brown, "and although their evolution was likely driven by an aspect of display, if push came to shove, would have been used in defence if needed."

The only way to figure out the finer details of these anatomical mysteries is to keep searching for new specimens, and to continue looking for new clues on those that are already excavated. Along those lines, Brown and his co-author Donald Henderson are working to reconstruct the spectacular Regaliceratops skull in greater detail.

"Although the skull is nearly 100 percent complete, it has been deformed due to the tectonic forces in the host rocks," explained Brown. "One of the main projects for my co-author on the study is to attempt to un-deform the skull to figure out exactly what the animal looked like originally."

Given all the insights it has offered Brown and Henderson so far, no doubt the new species has even more surprises up its ceratopsid sleeve. Triceratops may be the most famous of the horned dinosaurs, but Regaliceratops is certainly shaping up to be among the weirdest.