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Triceratops

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Triceratops /traɪ'sɛ.ræ.tɒps/ meaning "three-horned face", derived from the Greek "tri -/τρι-" =three, "cerat-/κερατ-" =horn, "-ops/ωψ" = face) was a ceratopsid herbivorous dinosaur genus from the Latest Cretaceous period of North America. It lived on earth around 70-65 million years ago. It was about 9 m (30 ft) long, ten feet tall, and probably weighed around 5,400 kg (12,000 lb).

Discoveries and species

Triceratops skull, showing horns and frill (neck armour?) Oxford University Museum of Natural History
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Triceratops skull, showing horns and frill (neck armour?) Oxford University Museum of Natural History

Triceratops was discovered by John Bell Hatcher in 1888. Its declaration as a legitimate dinosaur came when an intact skull was found. It was named by Othniel Charles Marsh in 1889. Some time earlier, however, in 1887 near Denver, Colorado, USA, he had misidentified the Triceratops as a type of bison, giving it the name Bison alticornis. The sturdy nature of the animal's skull has ensured that many examples have been preserved as fossils, allowing variations between species and individuals to be studied. Triceratops remains have subsequently been found in Montana and Wyoming, in the USA and in Saskatchewan and Alberta, in Canada.

How many species?

In the first decades after Triceratops was described, various skulls were collected which varied to a lesser or greater degree from the original Triceratops, named T. horridus by Marsh. Disoverers would write these up as separate species (listed below). However eventually the idea that the differing skulls might be representative of individual variation within one (or two) species gained popularity. In 1986, Ostrom and Wellnhofer Ostrom, J. H., and P. Wellnhofer. 1986. The Munich specimen of Triceratops with a revision of the genus. Zitteliana 14: 111 - 158.published a paper where they proposed there was only one species - Triceratops horridus. Part of the rationale is that generally there are only one or two species of any large animal in a region (e.g. elephant or giraffe in Africa). A few years later, Cathy Forster reanalysedForster CA (1996): Species resolution in Triceratops: cladistic and morphometric approaches. J.Vert.Paleont. 16(2): 259-270 Triceratops material more comprehensively and felt the remains fell into two species, T. horridus and T. prorsus, though the distinctive skull of T. (now tentatively Diceratops) hartcheri differed enough to warrant a separate genus.

Triceratops species:

Nomina dubia:

Misassignments:

Paleobiology

Paleontologists deduce from the evidence of ichnites (fossilised footprints) of dozens of individual animals, that Triceratops lived in herds, similar to those of modern-day buffalo.

Dentition

Its food was plants and shrubbery and its snout consisted of a sharp beak, which would have enabled it to break up and eat very tough vegetation. This beak could also be used in self-defence, as in the case of the primitive horned dinosaur Protoceratops. Behind the beak, Triceratops had a series of teeth arranged in a shearing mechanism. Triceratops teeth are among the most abundant fossils in the Late Cretaceous of Western North America (65 mya), suggesting that it was the dominant herbivore of the time.

Gait

Triceratops possessed a sturdy build, with robust legs and five-hoofed toes. It is estimated that Triceratops was able to run at around 24 km/h (15 mph), since its short legs meant it could not take long strides.

Horns and frill

Triceratops head from the front
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Triceratops head from the front

Triceratops head from the side
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Triceratops head from the side

The distinctive skull of Triceratops had a single horn on the snout, above the nostrils and a pair of horns approximately 1 m (3 ft) long, above the eyes. The rear of the skull bore a relatively short bony frill.

A number of functions have been proposed for the frill:

In 2005, a BBC documentary, The Truth About Killer Dinosaurs, tested how Triceratops might have defended itself against large predators like Tyrannosaurus. To see if Triceratops could have charged other dinosaurs, as would a modern-day rhinoceros, an artificial Triceratops skull was made and propelled into simulated Tyrannosaurus skin, at 24 km/h (15 mph). The brow horns penetrated the skin but the blunt nose horn and the beak could not and the front of the skull broke. The program therefore concluded that it would have been impossible for Triceratops to have defended itself in this way - instead, it probably stood its ground when attacked by large predators, using its horns for goring if the predator came close enough.

A recent study Goodwin MB, Clemens WA, Horner JR, Padian K: The smallest known Triceratops skull: new observations on Ceratopsid cranial anatomy and ontogeny, Journal of Vertebrate Paleontology, 2006, 26(1):103-112 of the smallest Triceratops skull, ascertained to be a juvenile, shows the frills and horns developed at a very early age, predating sexual development and thus possibly important for visual communication and species recognition.

Depiction in popular media

References

  • Dodson, P. (1996). The Horned Dinosaurs. Princeton University Press, Pinceton, New Jersey, pp. xiv-346

External links

Wikibooks has a manual, textbook or guide to this subject:

 


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