When famed paleontologist Othniel Charles Marsh first discovered a Triceratops fossil in 1887, he mistakenly identified it as belonging to a particularly large and unusual bison, which he named Bison alticornis. Another Triceratops fossil was discovered a year later by John Bell Hatcher, and in 1889, Marsh finally realized his mistake.

Triceratops, which may have lived in herds like modern buffalo, had three distinctive horns -- one on its snout and two more above the eyes. Along with the bony frill that protected the rear of its skull, these horns provided a natural defense against the attacks of other dinosaurs, but the Triceratops was himself an herbivore, feeding on plants and shrubbery.

The species first appeared during the Maastrichtian stage of the Late Cretaceous period, about 68 million years ago in what is now North America. It is one of the last-known non-avian dinosaur genera, and became extinct in the Cretaceous-Paleogene extinction event 66 million years ago.

Part of what makes Triceratops so recognizable is its enormous skull, which, with its backward-pointing frill, could attain a length of over eight feet and reach almost a third of the length of the entire animal.

One of the lesser-known facts about dinosaurs such as Triceratops is that they had birdlike beaks that could clip off hundreds of pounds of tough vegetation (including cycads, ginkgoes, and conifers) every day.

Most of the skull was covered by indentations made by blood vessels. Similar indentations are found under the keratinous beaks of living birds. This suggests that the entire head of Triceratops, aside from the cheeks and the area around the nostrils, was covered in keratin while it was alive. In many living birds, keratin is very colorful, a fact that suggests that the skulls of Triceratops may have been very colorful as well.

Analysis of the endocranial anatomy suggests that its sense of smell was poor compared to that of other dinosaurs.

One of the most recognizable of all dinosaurs and the most well-known ceratopsid, it was also one of the largest--up to 9 meters (30 ft) long and 12 metric tons (13 short tons) in weight.

Research published in 2010 concluded that the contemporaneous Torosaurus, a ceratopsid with a frilled skull that reached up to 2.77 metres (9.1 ft) in length, represents Triceratops in its mature form. This view was almost immediately disputed with examination of more fossil evidence needed to settle the debate.

It had up to 800 teeth (although only a fraction were in use at any given time) that were constantly being replenished, and were arranged in groups called batteries, with each battery having 36 to 40 tooth columns in each side of each jaw and three to five teeth per column. The great size and numerous teeth of Triceratops suggest that it ate large volumes of fibrous plant material, with some researchers suggesting palms and cycads.