The giant creature may be the oldest known cousin of Triceratops and Torosaurus - the best-known horned dinosaurs - yet, researchers say.
Judiceratops tigris has been identified based on fossils from north central Montana, further underscoring the diversity of large, plant-eating horned dinosaurs among the fauna of western North America 66 to 80 million years ago.
By now, fossil remains of at least 18 closely related dinosaurs from the region have been identified as distinct species, and Yale researcher Nicholas Longrich expects others will be discovered.
"These species show up for just a couple million years, or even a far shorter time, before another species replaces it. As you move up into younger rocks or down into older rocks, you get new species and no longer see the old ones. There was a lot of turnover," said Longrich.
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Identified by analysis of skull fragments belonging to four previously collected specimens in the Peabody's collection, Judiceratops lived during the late Cretaceous era, about 78 million years ago, or 12 million years before the more familiar Triceratops and Torosaurus.
Judiceratops was likely a large plant-eating dinosaur that fed on low-growing vegetation, such as ferns, like other members of its family. It had two large horns over the brow and a smaller horn on its nose.
The three-horned Judiceratops differs from all other horned dinosaurs in the shape and arrangement of the scallops on the edge of the frill, which are large and triangular toward the front, and low and blunt toward the back.
"These are very bold, conspicuous display structures," Longrich said of the frills, which might also have served a defensive purpose.