Classification
The Discovery
In the early days of paleontology - the 1850s, 60s and 70s - a number of unidentifiable bone fragments had been found. It wasn't until 1887, however, that the first major Triceratops ("Three-horned head") remains were located - a pair of hone cores, the bone around which the horns would have grown in the live animal. However, pioneering paleontologist Othniel Charles Marsh dismissed them as buffalo remains.
In 1888 professional collector John Bell Hatcher discovered a complete skull in Wyoming, USA and took it to Marsh. Marsh conceded his earlier mistake and published his description of Triceratops in 1889.
Description
In addition to being the largest of ceratopsians, Triceratops was something of an exception among them. Most short-frilled ceratopsians, such as Styracosaurus, had just a single facial horn. Triceratops, famously, has two further horns on its brow, of varying size (see Species discussion below). These horns were used to defend itself against predators and also as part of the mating ritual. Also, the bone structure of the neck frill was solid in Triceratops, while most other ceratopsians had large hollows like those of Chasmosaurus. Frills had originally evolved as an extended anchor for the powerful mandible (lower jaw), but Triceratops' also offered very effective protection for the neck.
Although we have reconstructed the complete skeleton of Triceratops from numerous separate finds, it is in discussion of the skull that we can be most confident. For many species, a skull is a rare find since they are flimsy frameworks built from easily-broken struts. Triceratops skulls, on the other hand, are a single solid lump of bone and therefore are frequently found relatively well-preserved. The skull alone could measure over two metres in length! This is the largest skull any land animal has ever possessed.
Triceratops is often depicted in combat with Tyrannosaurus rex. It is likely that such scenes did occur, since these two animals occupied the same part of the world at about the same time. Indeed, some T. rex coprolite (fossilized droppings) has recently been found and a fragment of bone located therein has been tentatively identified as from the frill of a Triceratops.
Species of Triceratops
The number of identified species of Triceratops is still a contentious issue among paleontologists. A number of different skulls have been recovered, and initially many of these were classified as separate species; T. horridus, T. prorsus, T. albertensis, T. ingens, T. alticornis and more. This view was challenged by Ostrom and Welnhoffer in 1990, who claimed that there was just one species and that the differences between the skulls can be attributed to individual variation within species. In 1996, C. Forster published his belief that there were certainly two species and possible more. There is no general consensus among paleontologists at this time, but the most familiar depiction of Triceratops is as T. horridus.
Factual Round-Up
Triceratops was one of the last dinosaurs to evolve, appearing from 72 to 65 million years ago, in the late Cretaceous. It was the largest of all ceratopsians, at 9 metres long and weighing around 10.5 tonnes. Like all ceratopsians, it was a strict herbivore and probably browsed low foliage such as cycads. All skeletons so far recovered have been found in North America.
Triceratops had very powerful legs to support its large mass, but analysis of its tracks reveals that it was probably a slow-moving dinosaur. Like other ceratopsians, Triceratops probably existed in herds and so its sloth would not have made it any more vulnerable.
Triceratops is one of the best-loved of all dinosaurs and a good skeleton can be seen in the London National History Museum.
One final piece of trivia: recent analysis of Triceratops' skull indicates that it had an exceptional sense of smell!