The Triceratops (meaning "three-horned face") is a dinosaur that lived between 68 and 65 million years ago. It was one of the last dinosaur genera to emerge before all non-avian dinosaurs were wiped out in the Cretaceous-Tertiary extinction, thought to have been caused by the impact of a massive (6-10 mi diameter) asteroid on the modern-day Yucatán Peninsula in Mexico. Triceratops was contemporaneous with the famous Tyrannosaurus Rex. It is not known whether Triceratops and the T. Rex had epic battles like those portrayed in children's coloring books about dinosaurs, although is is known that T. Rex preyed upon Triceratops, as determined by the presence of teeth lacerations on the bones of some Triceratops fossils.
Triceratops has been described by some as the dinosaur analog of a rhinoceros. It walked on four legs and had large frills to accompany its three huge horns. Although sometimes the horns are described as defensive weapons, it is more likely they were merely used in courtship displays, as are the horns of modern reindeer, mountain goats, or rhinoceros beetles.
Triceratops dimensions were between 7.9 to 9.0 m (26.0–29.5 ft) in length, 2.9 to 3.0 m (9.5–9.8 ft) in height, and 6.1–12.0 tonnes (13,000-26,000 lb) in weight. The most distinctive feature of Triceratops was its huge skull, which could be as as long as 2 m (7 ft), and be as long as a third of the entire animal. Triceratops' head is the largest of any land animal, living or dead.
Triceratops has been used as a reference point in phylogenetics. "Dinosaurs" have been formally defined as all animals descending from the most recent common ancestor of Triceratops and modern birds.
No complete Triceratops fossil has ever been found, although many fragments have. The first Triceratops bones were found in Denver, Colorado in the spring of 1887, consisting of two large horns connected to the skull roof. At first, it was thought that these belonged to an extraordinarily large and extinct bison. After several other skulls were found, it was realized that horned dinosaurs did exist, and the genera of Triceratops was founded to classify the fossils. Due to the extremely sturdy nature of the Triceratops skull, many have been found, allowing for comparisons between Triceratops of different ages and regions.
Although Triceratops had a huge head, it had a very tiny brain, just about the size of a man's fist. From this, we can make an educated guess that the Triceratops was not very intelligent.