Triceratops

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Triceratops horridus
Triceratops
Triceratops (XL figure)
Baby Triceratops

Triceratops (Tri-seh-rah-tops)literally ‘three horned face’, was a large herbivorous dinosaur that lived during the end of the Cretaceous Period (68-66 million years ago) in what is now western North America. One of the last dinosaurs to have lived before the great extinction event, it shared its world with other dinosaurs such as the duckbill Edmontosaurus, the armoured dinosaur Ankylosaurus, and the carnivorous Tyrannosaurus. Triceratops belongs to a group of dinosaurs called ceratopsids, commonly called ‘horned dinosaurs’. Although primitive relatives without horns have been discovered in Asia, true horned dinosaurs are known only from North America.


Content List

1. Genera & species

2. Characteristics

a. Size

b. Behavior

3. History of Discovery

4. Paleoenvironment

5. References


Genera and Species

Classification: Marginocephalia, Ceratopsia, Ceratopsidae


Species: At one time, up to 16 separate species have been recognized. However, most of these ‘species’ are now thought to be slight variations on the ‘typical’ Triceratops, and not distinct species. Currently, only two species are recognized: Triceratops horridus lived for about one million years, and then went extinct. It was replaced by Triceratops prorsus, that lived to the end of the Cretaceous, when all dinosaurs became extinct. The two species of Triceratops have slightly different skull and horn shapes, but were otherwise very similar.



Characteristics

Both Triceratops species have a horn on snout (although the horn is larger and more erect in T. prorsus), and a horn over each eye. The skull has a bony, saddle-shaped ‘frill’ that projects back over the neck, making the head look gigantic. The horns probably were used to fend off predators like Tyrannosaurus, but may also have been used to combat other Triceratops. Young Triceratops had a much shorter frill and very short horns.


Size

LENGTH: 9 m (30 ft).

WEIGHT: An adult would have been at least 6 tons, and the largest individuals would have exceeded 10 tons.


Behavior

Triceratops was a plant eater, using its horny beak to crop vegetation, which was then sliced up using a battery of sharp teeth further back in the jaws. Triceratops may have travelled in herds, like other horned dinosaurs, but we do not yet have fossil evidence that they did. Both males and females had horns, suggesting that they were used as defense against predators, but it seems likely that the males also used the horns to fight other males for dominance. Although the ‘frill’ at the back of the skull may have been used to protect the neck from the teeth of a Tyrannosaurus, it may also have been used to display to other Triceratops, much as birds spread their feathers to impress potential mates and ward off competitors.


History of Discovery

Triceratops is one the very first North American dinosaurs to be discovered and described. A famous paleontologist, Othneil Marsh, working at Yale University, sent may expeditions to the American west in the years following the Civil War, and collected many Triceratops skeletons. He published a description of some this material, and named Triceratops in 1889. Many more skeletons have been collected over the years since, but only large adults were found. Then about 15 years ago, a tiny Triceratops skull was collected. It showed clearly the tiny horns and short ‘frill’ that marks it as a baby.


Paleoenvironment

Many Triceratops skeletons have been found in sediments deposited on the coastal lowlands of an inland sea that covered much of central North America during the Cretaceous Period, suggesting that this was their preferred habitat. They competed for food with the duckbill Edmontosaurus and armoured dinosaur Ankylosaurus, and were preyed upon by Tyrannosaurus.


References

1. Paul, G. (2010). The Princeton Field Guide to Dinosaurs (pp. 6132). Princeton, New Jersey: University Press Princeton.
2. Worth, G. (1999). The Dinosaur Encyclopaedia (pp. 2281). Scarborough, Western Australia: HyperWorks Reference Software.
3. Goodwin, M.B., Clemens, W.A., Horner, J.R., and Padian, K. 2006. The smallest known Triceratops skull: New observations on ceratopsid cranial anatomy and ontogeny. 
Journal of Vertebrate Paleontology 26:103-112.