Triceratops is a genus of herbivorous ceratopsid dinosaur that first appeared during 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. Its head bore a large bony frill and three horns while its body was massive and four-legged. It shared the landscape with and was probably preyed upon by the fearsome Tyrannosaurus.
The exact placement of the Triceratops genus within the ceratopsid group has been debated by paleontologists. Two species, T. horridus and T. prorsus, are considered valid. Research published in 2010 suggests that the contemporaneous Torosaurus, a ceratopsid long regarded as a separate genus, represents Triceratops in its mature form, a view not accepted by all researchers. Triceratops has been documented by numerous remains collected since the genus was first described in 1889, including at least one complete individual skeleton. Specimens representing life stages from hatchling to adult have been found.
The function of the frills and three distinctive facial horns has long inspired debate. Traditionally these have been viewed as defensive weapons against predators. More recent theories, noting the presence of blood vessels in the skull bones of ceratopsids, find it more probable that these features were primarily used in identification, courtship and dominance displays, much like the antlers and horns of modern reindeer, mountain goats, or rhinoceros beetles. (see more...)