 Ceratopsia or <unk> ( / <unk> / or / <unk> / ; Greek : " horned faces " ) is a group of herbivorous , <unk> dinosaurs that <unk> 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 <unk> , lived between 161 @.@ 2 and 155 @.@ 7 million years ago . The last ceratopsian species , Triceratops <unk> , became extinct during the Cretaceous – <unk> extinction event , 66 million years ago . 
