Triceratops relative reveals dino diversity

One of science’s best-understood dinosaur groups was probably much more diverse than previously thought.

relative of Triceratops illustrationA newly discovered species, Regaliceratops peterhewsi, stands out among the subfamily of horned dinosaurs known as chasmosaurines, scientists at the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta, report in the June 15 Current Biology.

R. peterhewsi, a close relative of Triceratops, lived during the Late Cretaceous epoch, around 68 million years ago. Study authors Caleb Brown and Donald Henderson estimate thatR. peterhewsi was 5 meters long and weighed 1.5 metric tons. It received its regal title partly for the distinctive “crown” of plates around its head. The dinosaur’s fossil specimen, a nearly intact skull, goes by the less lofty nickname “Hellboy,” prompted by its devilishly hard excavation from a steep cliff in southwestern Alberta, where it was discovered in 2005. The nickname is also apt because R. peterhewsi had eye horn “nubbins” that made it resemble the comic book character of the same name, Brown says.

fossilized skull of Regaliceratops peterhewsi

HELLBOY The fossilized skull of Regaliceratops peterhewsi measures over 1.5 meters in length. The fossil was discovered in 2005 in a steep cliff along the Oldman River of southwestern Alberta in Canada.By analyzing its snout, the scientists determined that R. peterhewsi was a chasmosaurine. “Prior to the discovery of this animal, we had a pretty well-understood idea of the variation that we see in these chasmosaurines,” Brown says. Most of these dinosaurs, especially those that lived around the same time as R. peterhewsi, had long eye horns, short nose horns and a long but simple frill. But R. peterhewsi had surprisingly short eye horns compared with its long nose horn and a short but heavily ornamented frill. This discovery indicates that horned dinosaurs had much greater physical variation than scientists realized, Brown says.

Paleontologist Andrew Farke of the Raymond M. Alf Museum of Paleontology in Claremont, Calif., agrees that R. peterhewsi was an oddball. “It looks like a conglomeration of many different dinosaurs,” he says. “It’s very similar to a lot of horned dinosaurs it’s not closely related to.”

In fact, R. peterhewsi resembled members of a different horned dinosaur subfamily that went extinct around 2 million years before R. peterhewsi’s time. The new dinosaur seems to have independently evolved features similar to its predecessors’, a process known as convergent evolution. Scientists think that these physical similarities may indicate behavioral similarities between these dinosaurs, perhaps in the animals’ fighting styles. In modern horned mammals, for instance, species with similarly shaped horns tend to engage in similar behaviors like horn locking or head butting.

Farke says this finding will encourage paleontologists to look for other examples of convergent evolution and new ways to identify it. Discovering unexpected diversity in a relatively well-understood dinosaur group indicates how much remains unknown, Brown adds. “There’s still a lot of new dinosaurs to find.”

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