 Ceratopsia or Ceratopia ( / ˌsɛrəˈtɒpsiə / or / ˌsɛrəˈtoʊpiə / ; Greek : " horned faces " ) is a group of herbivorous , beaked dinosaurs that thrived in what are now North America , Europe , and Asia , during the Cretaceous Period , although ancestral forms lived earlier , in the Jurassic . The earliest known ceratopsian , Yinlong downsi , lived between 161 @.@ 2 and 155 @.@ 7 million years ago . The last ceratopsian species , Triceratops prorsus , became extinct during the Cretaceous – Paleogene extinction event , 66 million years ago . 
