Easily one of the most famous dinosaurs, Triceratops lived in North America 65-68 million years ago. They were up to 25 feet long or more and 5-7 tons in weight. Triceratops' famous horns were up to 3 feet long! Numerous Triceratops bones have been found with Tyrannosaurus bite marks on therm. This suggest frequent interaction between the two. Due to the large number of fossils, Triceratops is among the best known dinosaurs to science.