See the skeleton Triceratops Kingdom Animalia (animals) Phylum Chordata (animals with spinal nerve cords) Subphylum Vertebrata (chordates with backbones) Class Archosauria ("ruling reptiles") Subclass Dinosauria (extinct reptiles, "terrible lizards") Order Ornithischia (beaked, bird-hipped plant eaters) Suborder Marginocephalia (fringed heads) Family Ceratopsidae (frilled dinosaurs, including horned dinosaurs) Genus Triceratops (three-horned face) Species horridus (horrible)

Meet Kelsey the Triceratops

Kelsey is a Triceratops horridus which means "horrible three-horned face." Why do you think they named this type of dinosaur that way?

Kelsey lived in the late Cretaceous Period, more than 65 million years ago. Triceratops like Kelsey could be found in the western part of the United States and in southwestern Canada.

You can tell Kelsey is a Triceratops by the three horns on its head. Scientists call a horned dinosaur like Triceratops a ceratopsian. The two horns above the eye sockets were up to 3 feet long. The horns were sharp and covered with a thick coat of the same stuff your fingernails are made of, called keratin, which made them strong. They came in handy in a fight with any T. rex that decided Kelsey would make a nice meal.

Although Kelsey wasn't a predator looking for a fight, it wasn't defenseless if attacked. In addition to having horns, Triceratops could use its size to defend itself. Triceratops could be as tall as a basketball goal (10 feet), and as long as three basketball goals laid end-to-end (30 feet), and could weigh as much as three cars (six tons).

A Triceratops' eyes also helped it defend itself. They were on the sides of its head and helped it scan for any predators coming after it.

You can't miss the big bone sticking up at the back of Kelsey's head. This bone is called a frill and scientists used to think it was there to protect the neck area. Some scientists now think the frill may have been important in helping male Triceratops attract females or distract potential male rivals for a female's attention. Another possible explanation for the frill is heat regulation. As the Triceratops' body warmed up, heat escaped from the frill and the body temperature returned to normal.

Kelsey was a herbivore, which means it ate plants instead of meat. Because a Triceratops was so big, it ate many pounds of plants a day. It ate low-lying plants such as ferns and cycads. Scientists think it may have used its horns to knock down small trees and then snipped off the leaves with its parrot-shaped beak. Scientists know some of the plants it ate by studying phytoliths, tiny parts of plants that left scratch marks on fossilized dinosaur teeth or remained between teeth after they fossilized.

Scientists debate whether Triceratops lived in herds. Some think they might have roamed the Cretaceous forests on their own and did not migrate.

Interesting Things About Kelsey

Like other Triceratops, Kelsey had a big head. It was as long as a human adult is tall (over 6 feet) and was nearly one-third as long as its body. The fossilized bone of the skull is up to 2 inches thick and is very heavy. The skull is bumpy (scientists refer to this as "rugosity"). Some scientists think this bumpiness might have been a sign of old age.

No dinosaur is discovered 100 percent complete. Due to erosion and other factors, some fossilized bones are always missing. The people who prepare the dinosaurs for exhibits create casts of the missing bones, usually from other dinosaurs that have been discovered, to fill in the missing pieces. Very few Triceratops have been found and most of the ones that have been found aren't very complete. More than 50 percent of Kelsey's skeleton has been found, which makes it possibly the most complete Triceratops ever found and one of the top three ever discovered.

No big toothmarks were found on Kelsey, so maybe T. rex never gave it a bad bite. Several tiny bite marks were found on Kelsey's leg bone.

Kelsey's Discovery

Kelsey was discovered by the Leonard and Arlene Zerbst family in the fall of 1997 on their ranch in Niobrara County, Wyoming. The ranch is part of the Lance Creek fossil bed, where the fossils of many dinosaurs from the Late Cretaceous Period have been found. The Zerbsts named Kelsey after their 3-year old granddaughter, Kelsey Ann.

Alongside Kelsey were found more than 20 fossilized teeth of a predatory dinosaur, Nanotyrannus, a smaller cousin of T. rex. Did the Nanotyrannus kill Kelsey, or did Kelsey die of natural causes and the Nanotyrannus just happen along to scavenge on the already dead Triceratops? Does this explain the tiny bite marks found on Kelsey's leg?