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Triceratops

2007 Schools Wikipedia Selection. Related subjects: Dinosaurs

         iTriceratops

                        Fossil range: Late Cretaceous

   Triceratops skeleton at the National Museum of Natural History.
   Triceratops skeleton at the
   National Museum of Natural History.

                             Conservation status

   Extinct (fossil)
                      Scientific classification

   Kingdom:    Animalia
   Phylum:     Chordata
   Class:      Sauropsida
   Superorder: Dinosauria
   Order:      Ornithischia
   Suborder:   Marginocephalia
   Infraorder: Ceratopsia
   Family:     Ceratopsidae
   Subfamily:  Ceratopsinae
   Genus:      Triceratops
               Marsh, 1889

                                   Species

   See text.

   Triceratops (traɪ'sɛ.ræ.tɒps) meaning 'three-horned face' (derived from
   the Greek tri -/τρι- meaning 'three', ceras/κέρας meaning 'horn' and
   -ops/ωψ meaning 'face') was a ceratopsid herbivorous dinosaur genus,
   from the Late Cretaceous Period (from around 70-65 million years ago)
   of what is now North America. It lived at around the same time and
   place as Tyrannosaurus, Ankylosaurus and another well-known ceratopsid,
   Torosaurus.

   Although no complete skeleton has been found, it has been estimated
   that Triceratops was about 9 m (30 ft) long, 3 m (10 ft) tall, and
   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
   Enlarge
   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, South Dakota, 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 (from Latin horridus;
   "rough, rugose", suggesting the roughened texture of the bones, which
   Marsh later admitted belonged to an aged individual). Discoverers would
   write these up as separate species (listed below). Eventually, however,
   the idea that the differing skulls might be representative of
   individual variation within one (or two) species gained popularity. In
   1986, Ostrom and Wellnhofer 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 modern Africa). A few years
   later, Cathy Forster reanalysed Triceratops material more
   comprehensively and concluded that the remains fell into two species,
   T. horridus and T. prorsus, although the distinctive skull of T. (now
   tentatively Diceratops) hatcheri differed enough to warrant a separate
   genus.Chris Ogborne Rules

   Triceratops species:
     * T. horridus Marsh, 1889 ( type species)
     * T. prorsus Marsh, 1890

   Triceratops model, Royal Belgian Institute of Natural Sciences,
   Brussels
   Enlarge
   Triceratops model, Royal Belgian Institute of Natural Sciences,
   Brussels

   Nomina dubia:
     * T. albertensis Sternberg, 1949
     * T. alticornis Marsh, 1887 (originally 'Bison')
     * T. eurycephalus Schlaikjer, 1935
     * T. galeus Marsh, 1889
     * T. ingens Lull, 1915
     * T. maximus Brown, 1933
     * T. sulcatus Marsh, 1890

   Misassignments:
     * T. brevicornis Hatcher, 1905 (=T. prorsus)
     * T. calicornus Marsh, 1898 (=T. horridus)
     * T. elatus Marsh, 1891 (=T. horridus)
     * T. flabellatus Marsh, 1889 (=T. horridus)
     * T. hatcheri Lull, 1907 (=Diceratops hatcheri)
     * T. mortuarius Cope, 1874 (also nomen dubium; originally Polyonax;
       =Polyonax mortuarius)
     * T. obtusus Marsh, 1898 (=T. horridus)
     * T. serratus Marsh, 1890 (=T. horridus)
     * T. sylvestris Cope, 1872 (nomen dubium; originally Agathaumas;
       =Agathaumas sylvestris)

Paleobiology

   Although Triceratops is commonly portrayed as a herding animal, there
   is currently no solid evidence that it lived in herds. Unlike other
   horned dinosaurs, some of which are known from sites preserving dozens
   or hundreds of individuals, all Triceratops finds known at present
   preserve only solitary individuals.

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-defense, as in the
   case of the primitive horned dinosaur Protoceratops. Behind the beak,
   Triceratops had a series of teeth arranged in a shearing configuration.
   Triceratops teeth are among the most abundant fossils in the Late
   Cretaceous Period 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.

Posture

   The posture of Triceratops has long been the subject of some debate.
   Originally, it was believed that the front legs of the animal had to be
   sprawling at angles from the thorax, in order to better bear the weight
   of the head. This stance can be seen in paintings by Charles Knight and
   Rudolf Zallinger. However, ichnological evidence in Triceratops
   trackways seem to show that Triceratops maintained an upright stance
   during normal locomotion, with the knees slightly bowed out (as in the
   modern rhinoceros). This does not preclude a sprawling gait for
   confrontations or feeding.

Horns and frill

   Triceratops head from the front
   Enlarge
   Triceratops head from the front
   Triceratops head from the side
   Enlarge
   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, 4 in)
   long, above the eyes. The rear of the skull bore a relatively short
   bony frill. Most other frilled dinosaurs had large fenestrae in their
   frills, while the frill of Triceratops is noticeably solid.

   A number of functions have been proposed for the frill:
     * Defense against carnivores, such as Tyrannosaurus
     * Communication between herd members
     * Battling rival Triceratops over status, resources or territory
     * Courtship display
     * A status symbol which reflects (or determines) the individual's
       status in the herd
     * Anchor points for the jaw muscles
     * Increasing body area, to regulate body temperature (see also:
       thermoregulation)

   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
   conclusion drawn was 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 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.
   Retrieved from " http://en.wikipedia.org/wiki/Triceratops"
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