Ancient cousin of Triceratops highlights turnover among horned dinosaurs

The earliest known cousin of Triceratops and Torosaurus - the best-known horned dinosaurs - 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. "We keep finding new species, because cerotopsids - horned dinosaurs - evolved so rapidly," said Longrich, the postdoctoral researcher who identified the latest addition to the family, Judiceratops tigris . "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." Longrich reports the details of his research in a paper published in the spring edition of the Bulletin of the Peabody Museum of Natural History. 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.