Triceratus

Triceratus (name meaning Three horns) is an extinct species of Cerotopsid (a group of dinosaurs that also includes Triceratops, the ancestors of Triceratus) dinosaur that was among the last ever true horned dinosaur native to North America to go extinct, which was the only one to make it through the K-T extinction, along with the Micropachyrhinus. It evolved from a group of triceratops that have made it into vegetation-filled islands that were untouched by the asteroid that caused the extinction of most non-avian dinosaurs, after the extinction was over, the remaining Triceratops made it back onto mainland, finding less food than there were, so they shrank over time until they were only twice the size of a white rhinoceros. They were herbivores that mainly fed on leaves, fruits, cycads, ferns, and horsetail. The reason for its extinction is not known, but it is possible that it was outcompeted to extinction in the Early Eocene (around 50-45 million years ago) by newly-arriving large mammal herbivores such as Uintatherium and others.