Triceratops
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Reverted edits by [[Special:Contributions/82.133.29.98|82.133.29.98]] to last version by Closedmouth (using [[WP:HG|Huggle]])
{{Taxobox
| name = ''Triceratops''
| fossil_range = [[Late Cretaceous]]
| image = Triceratops2.png
| image_width = 250px
| image_caption = ''Triceratops'' skull, showing horns and frill, [[Oxford University Museum of Natural History]].
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Reptile|Sauropsida]]
| superordo = [[Dinosaur]]ia
| ordo = [[Ornithischia]]
| subordo = [[Cerapoda]]
| infraordo = [[Ceratopsia]]
| familia = [[Ceratopsidae]]
| subfamilia = [[Ceratopsinae]]
| genus = '''''Triceratops'''''
| genus_authority = [[Othniel Charles Marsh|Marsh]], 1889
| subdivision_ranks = [[Species]]
| subdivision =
* ''T. horridus'' <small>Marsh, 1889 ([[Type (zoology)|type]])</small>
* ''T. prorsus'' <small>Marsh, 1890</small>
| synonyms =
* ''Sterrholophus'' <small>Marsh, 1891</small>
* ''[[Claorhynchus]]''? <small>[[Edward Drinker Cope|Cope]], 1892</small>
* ''Ugrosaurus'' <small>Cobabe & Fastovsky, 1987</small>
}}
'''''Triceratops''''' ({{pronEng|traɪˈsɛrətɒps}}) is an extinct [[genus]] of [[herbivore|herbivorous]] [[Ceratopsidae|ceratopsid]] [[dinosaur]] that lived during the [[Maastrichtian|late Maastrichtian]] stage of the Late [[Cretaceous]] [[Period (geology)|Period]], around 68 to 65 [[mya (unit)|million years ago]] (mya) in what is now [[North America]]. It was one of the last dinosaur genera to appear before the great [[Cretaceous-Tertiary extinction event|Cretaceous–Tertiary extinction event]].<ref>{{cite journal|author=Lehman T.M.| date=1987| title=Late Maastrichtian paleoenvironments and dinosaur biogeography in the Western Interior of North America| journal=Paleogeography, Paleoacclimatology and Paleoecology| volume=60 | pages = 290| doi=10.2307/2406631}}</ref> Bearing a large bony [[neck frill|frill]] and three [[horn (anatomy)|horns]] on its large four-legged body, and conjuring similarities with the modern [[rhinoceros]], ''Triceratops'' is one of the most recognizable of all dinosaurs. The name ''Triceratops'', which literally means "three-horned face", is derived from the [[Ancient Greek|Greek]] ''tri/τρι-'' meaning "three", ''ceras/κέρας'' meaning "horn", and ''-ops/ωψ'' meaning "face".<ref>{{cite book|author=Liddell & Scott|year=1980|title=Greek-English Lexicon, Abridged Edition |publisher=Oxford University Press, Oxford, UK|isbn=0-19-910207-4}}</ref> Though it shared the landscape with and was [[predation|preyed upon]] by the fearsome ''[[Tyrannosaurus]]'', it is unclear whether the two battled the way they are commonly depicted in movies, children's dinosaur books and many cartoons.
Although no complete skeleton has been found,<ref name="Lambert93">{{cite book|title=The Ultimate Dinosaur Book|year=1993|author=Lambert, D.|pages=pp. 152—167|publisher=Dorling Kindersley, New York|isbn=1-56458-304-X}}</ref> ''Triceratops'' is well-known from numerous partial specimens collected since the introduction of the genus in 1887. The function of their frills and three distinctive facial horns has long inspired debate. Although traditionally viewed as defensive weapons against predators, the latest theories claim that it is more probable that these features were used in [[mating|courtship]] and dominance displays, much like the [[antler]]s and horns of modern [[reindeer]], [[mountain goat]]s, or [[rhinoceros beetle]]s.<ref name="Dodhorned">{{cite book|title=The Horned Dinosaurs|year=1996|author=Dodson, P.|publisher=Princeton University Press, Princeton, New Jersey|isbn=0-691-02882-6}}</ref>
''Triceratops'' is the best-known of the ceratopsids, though the genus's exact placement within the group has been a point of contention amongst [[paleontology|paleontologists]]. Two [[species]], ''T. horridus'' and ''T. prorsus'', are considered valid, although many other species have been named.
==Description==
[[Image:Human-triceratops size comparison.svg|thumb|left|''Triceratops'' compared in size with a human]]
Individual ''Triceratops'' are estimated to have reached about 7.9 to 9.0 [[metre|m]] (26.0–29.5 [[foot (unit of length)|ft]]) in length, 2.9 to 3.0 m (9.5–9.8 ft) in height,<ref name="dinodict">[http://www.dinodictionary.com/dinos_tpg2.asp DinoDictionary.com :: T Dinosaurs Page 2<!-- Bot generated title -->]</ref><ref name="nhm">[http://internt.nhm.ac.uk/jdsml/nature-online/dino-directory/detail.dsml?Genus=Triceratops Triceratops in The Natural History Museum's Dino Directory]</ref> and 6.1–12.0 [[tonne]]s (13,000-26,000 [[pound (mass)|lb]]) in [[weight]].<ref name="Alexander">Alexander, R.M. (1985). "Mechanics of posture and gait of some large dinosaurs." ''Zoological Journal of the Linnean Society'', 83, 1–25.</ref> The most distinctive feature is their large [[skull]], among the largest of all land animals. It could grow to be over 2 m (7 ft) in length,<ref name ="Dodhorned"/> and could reach almost a third of the length of the entire animal.<ref name="Lambert93"/> It bore a single horn on the snout, above the [[nostril]]s, and a pair of horns approximately 1 m (3 ft) long, with one above each eye. To the rear of the skull was a relatively short, bony frill. Most other frilled dinosaurs had large [[fenestrae]] in their frills, while the frills of ''Triceratops'' were noticeably solid.
[[Image:Triceratops Skeleton Senckenberg 2.jpg|thumb|left|Side view of ''Triceratops'' skeleton, Senckenberg Museum.]]
''Triceratops'' species possessed a sturdy build, with strong limbs and short five-hoofed hands and four-hoofed feet.<ref name="Dino2"/> Although certainly [[quadruped]]al, the posture of these dinosaurs 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.<ref name="Dodhorned"/> This stance can be seen in paintings by [[Charles R. Knight|Charles Knight]] and [[Rudolph F. Zallinger|Rudolph Zallinger]]. However, [[ichnology|ichnological]] evidence in the form of [[fossil trackway|trackway]]s from horned dinosaurs, and recent reconstructions of skeletons (both physical and digital) seem to show that ''Triceratops'' maintained an upright stance during normal locomotion, with the elbows slightly bowed out, in an intermediate state between fully upright and fully sprawling (as in the modern rhinoceros).<ref name="CP01">Christiansen, P., and Paul, G.S. (2001). Limb bone scaling, limb proportions, and bone strength in neoceratopsian dinosaurs. ''Gaia'' '''16''':13–29.</ref><ref name="CSJA01">Chapman, R.E., Snyder, R.A., Jabo, S., and Andersen, A. (2001). On a new posture for the horned dinosaur ''Triceratops''. ''Journal of Vertebrate Paleontology'' '''21''' (Supplement to Number 3), Abstracts of Papers, 61st Annual Meeting:39A–40A.</ref> This conclusion does not preclude a sprawling gait for confrontations or feeding.
==Classification==
[[Image:Triceratopsskull.jpg|thumb|Plate showing the skull of ''Triceratops prorsus'', published by Othniel Marsh in 1896.]]
''Triceratops'' is the best known genus of the [[Ceratopsidae]], a family of large North American [[Ceratopsia|horned dinosaurs]]. The exact location of ''Triceratops'' among the ceratopsians has been debated over the years. Confusion stemmed mainly from the combination of short, solid frills (similar to that of [[Centrosaurinae]]), and the long brow horns (more akin to [[Ceratopsidae|Ceratopsinae]], also known as Chasmosaurinae). In the first overview of horned dinosaurs, [[R. S. Lull]] hypothesized two lineages, one of ''[[Monoclonius]]'' and ''[[Centrosaurus]]'' leading to ''Triceratops'', the other with ''[[Ceratops]]'' and ''[[Torosaurus]]'', making ''Triceratops'' a centrosaurine as the group is understood today.<ref name="HML07">Hatcher, J. B., Marsh, O. C. and Lull, R. S. (1907) ''The Ceratopsia''. Government Printing Office, Washington, D.C. ISBN 0405127138.</ref> Later revisions supported this view, formally describing the first, short-frilled group as Centrosaurinae (including ''Triceratops''), and the second, long-frilled group as Chasmosaurinae.<ref name=LL15>Lambe, L.M. (1915). On ''Eoceratops canadensis'', gen. nov., with remarks on other genera of Cretaceous horned dinosaurs. ''Canada Department of Mines Geological Survey Museum Bulletin'' '''12''':1–49.</ref><ref name="RSL33">Lull, R. S. (1933) A revision of the Ceratopsia or horned dinosaurs. ''Memoirs of the Peabody Museum of Natural History'' '''3'''(3):1–175.</ref>
[[Image:Triceratops BW.jpg|thumb|left|Life restoration of ''Triceratops horridus'']]
In 1949, [[Charles Mortram Sternberg|C. M. Sternberg]] was the first to question this and favoured instead that ''Triceratops'' was more closely related to ''[[Arrhinoceratops]]'' and ''[[Chasmosaurus]]'' based on skull and horn features, making ''Triceratops'' a ceratopsine (chasmosaurine of his usage) genus.<ref name="CMS49">Sternberg, C. M. (1949). The Edmonton fauna and description of a new ''Triceratops'' from the Upper Edmonton member; phylogeny of the Ceratopsidae. ''National Museum of Canada Bulletin'' '''113''':33–46.</ref> However, he was largely ignored with [[John Ostrom]],<ref>Ostrom, J. H. (1966). Functional morphology and evolution of the ceratopsian dinosaurs. ''Evolution'' '''20''':220–227.</ref> and later David Norman, both placing ''Triceratops'' within Centrosaurinae.<ref>{{cite book |last=Norman |first=David |title=The Illustrated Encyclopaedia of Dinosaurs |year=1985 |publisher=Salamander Books |location=London |isbn=0-517-468905}}</ref>
Subsequent discoveries and analyses upheld Sternberg's view on the position of ''Triceratops'', with Lehman defining both subfamilies in 1990 and diagnosing ''Triceratops'' as ceratopsine (chasmosaurine of his usage) on the basis of several morphological features. In fact, it fits well into the ceratopsine subfamily, apart from its one feature of a shortened frill.<ref name="TML90">Lehman, T. M. (1990). The ceratopsian subfamily Chasmosaurinae: sexual dimorphism and systematics. in: Carpenter, K., and Currie, P. J. (eds.). ''Dinosaur Systematics: Perspectives and Approaches'', Cambridge University Press, Cambridge, pp. 211–229. ISBN 0-521-36672-0.</ref> Further research by [[Peter Dodson]], including a 1990 [[cladistics|cladistic]] analysis<ref>Dodson, P., and Currie, P. J. (1990). Neoceratopsia. 593–618. in Weishampel, D. B., Dodson, P., & Osmólska, H. (eds.). ''The Dinosauria'' University of California Press:Berkeley, pp. 593–618. ISBN 0-520-06727-4.</ref> and a 1993 study using RFTRA (resistant-fit theta-rho analysis),<ref>Dodson, P. (1993). [http://earth.geology.yale.edu/~ajs/1993/11.1993.07Dodson.pdf Comparative Craniology of the Ceratopsia.] In: ''American Journal of Science'' '''293''', pp. 200–234.</ref> a [[morphometrics|morphometric technique]] which systematically measures similarities in skull shape, reinforces ''Triceratops''' placement in the ceratopsine subfamily.
===Use in phylogenetics===
In [[phylogenetics|phylogenetic taxonomy]], the genus has been used as a reference point in the definition of Dinosauria; Dinosaurs have been designated as all descendants of the most recent common ancestor of ''Triceratops'' and [[Bird#Bird orders|Neornithes]] (i.e. modern [[bird]]s).<ref>Gauthier, J. A. (1986). Saurischian monophyly and the origin of birds. The Origin of Birds and the Evolution of Flight, K. Padian (ed.), ''Memoirs of the California Academy of Sciences'' '''8''':1–55.</ref> Furthermore, the bird-hipped dinosaurs, [[Ornithischia]], have been designated as all dinosaurs with a more recent common ancestor to ''Triceratops'' than modern birds.<ref>Sereno, P. C. (1998). A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. ''Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen'' '''210'''(1):41–83.</ref>
===Origins===
[[Image:Laramie-skull.jpg|thumb|left|Skull of ''Triceratops'' from the [[Laramie Formation]] of eastern [[Colorado]]. Based on the age of the Laramie Formation, it may be the oldest ''Triecratops'' known.]]
For many years the origins of ''Triceratops'' have been largely obscure. In 1922, the newly discovered ''[[Protoceratops]]'' was seen as its ancestor by [[Henry Fairfield Osborn]],<ref>Dodson, P. (1996). ''The Horned Dinosaurs''. Princeton University Press:Princeton, New Jersey, p. 244. ISBN 0-691-02882-6.</ref> but many decades passed before additional findings came to light. However, recent years have been fruitful for the discovery of several dinosaurs related to ancestors of ''Triceratops''. ''[[Zuniceratops]]'', the earliest known ceratopsian with brow horns, was described in the late 1990s, and ''[[Yinlong]]'', the first known [[Jurassic]] ceratopsian, in 2005.
These new finds have been vital in illustrating the origins of horned dinosaurs in general, suggesting an [[Asia]]n origin in the Jurassic, and the appearance of truly horned ceratopsians by the beginning of the late Cretaceous in North America.<ref name ="Dino2">Dodson, P., Forster, C. A, and Sampson, S. D. (2004) ''Ceratopsidae''. In: Weishampel, D. B., Dodson, P., and Osmólska, H. (eds.), ''The Dinosauria'' (second edition). University of California Press:Berkeley, pp. 494–513. ISBN 0-520-24209-2.</ref> As ''Triceratops'' is increasingly shown to be a member of the long-frilled Ceratopsinae subfamily, a likely ancestor may have resembled ''[[Chasmosaurus]]'', which thrived some 5 million years earlier.
==Discoveries and species==
[[Image:Triceratops prorsus old.jpg|thumb|Skeletal restoration of ''Triceratops prorsus'' by O.C. Marsh, 1913]]
The first named specimen now attributed to ''Triceratops'' is a pair of brow horns attached to a skull roof, found near [[Denver, Colorado]] in the spring of 1887.<ref name="KC06">Carpenter, K. (2006). [https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/Balticornis.pdf "''Bison''" ''alticornis'' and O.C. Marsh's early views on ceratopsians.] In: Carpenter, K. (ed.). ''Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs'' Indiana University Press:Bloomington and Indianapolis, pp. 349–364. ISBN 0-253-34817-X.</ref> This specimen was sent to [[Othniel Charles Marsh]], who believed that the [[geologic formation|formation]] from which it came dated from the [[Pliocene]], and that the bones belonged to a particularly large and unusual [[bison]], which he named ''Bison alticornis''.<ref name="OCM87">Marsh, O.C. (1887). Notice of new fossil mammals. ''American Journal of Science'' '''34''':323–331.</ref><ref name="KC06"/> He realized that there were horned dinosaurs by the next year, which saw his publication of the genus ''[[Ceratops]]'' from fragmentary remains,<ref name="OCM88">Marsh, O.C. (1888). A new family of horned Dinosauria, from the Cretaceous. ''American Journal of Science'' '''36''':477–478.</ref> but he still believed ''B. alticornis'' to be a Pliocene [[mammal]]. It took a third and much more complete skull to change his mind. The specimen, collected in 1888 by [[John Bell Hatcher]] from the [[Lance Formation]] of [[Wyoming]], was initially described as another species of ''Ceratops''.<ref name="OCM89a">Marsh, O.C. (1889a). Notice of new American Dinosauria. ''American Journal of Science'' 37:331–336.</ref> After reflection, however, Marsh changed his mind and gave it the generic name ''Triceratops'', accepting his ''Bison alticornis'' as another species of ''Ceratops''<ref name="OCM89b">Marsh, O.C. (1889b). Notice of gigantic horned Dinosauria from the Cretaceous. ''American Journal of Science'' '''38''':173–175.</ref> (it would later be added to ''Triceratops''<ref name="HML07"/>). The sturdy nature of the animal's skull has ensured that many examples have been preserved as [[fossil]]s, allowing variations between [[species]] and individuals to be studied. ''Triceratops'' remains have subsequently been found in the American states of [[Montana]] and [[South Dakota]] (in addition to Colorado and Wyoming), and in the [[Canada|Canadian]] provinces of [[Saskatchewan]] and [[Alberta]].
===Number of species===
[[Image:Triceratops AMNH 01.jpg|right|thumb|''Triceratops horridus'' [[skeleton]] at the [[American Museum of Natural History]] in New York City.]]
Within 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 the [[Latin]] ''horridus''; "rough, rugose", suggesting the roughened texture of those bones belonging to the type specimen, later identified as an aged individual). This variation is unsurprising, given that ''Triceratops'' skulls are large three-dimensional objects, coming from individuals of different ages and both sexes, and which were subjected to different amounts and directions of pressure during fossilization.<ref name="Dodhorned"/> Discoverers would name these as separate species (listed below), and came up with several [[phylogeny|phylogenetic]] schemes for how they were related to each other.
In the first attempt to understand the many species, Lull found two groups, although he did not say how he distinguished them: one composed of ''T. horridus'', ''T. prorsus'', and ''T. brevicornus''; the other of ''T. elatus'' and ''T. calicornis''. Two species (''T. serratus'' and ''T. flabellatus'') stood apart from these groups.<ref name="HML07"/> By 1933, and his revision of the landmark 1907 Hatcher-Marsh-Lull [[monograph]] of all known ceratopsians, he retained his two groups and two unaffiliated species, with a third lineage of ''T. obtusus'' and ''T. hatcheri'' that was characterized by a very small nasal horn.<ref name="RSL33"/> ''T. horridus''-''T. prorsus''-''T. brevicornus'' was now thought to be the most conservative lineage, with an increase in skull size and a decrease in nasal horn size, and ''T.-elatus''-''T. calicornis'' was defined by large brow horns and small nasal horn.<ref name="RSL33"/> C. M. Sternberg made one modification, adding ''T. eurycephalus'' and suggesting that it linked the second and third lineages closer together than they were to the ''T. horridus'' lineage.<ref name="CMS49"/> This pattern was followed until the major studies of the 1980s and 1990s.
[[Image:Triceratops Science Museum MN.JPG|left|thumb|''Triceratops prorsus'' at the Science Museum of Minnesota.]]
With time, 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 in which they proposed that there was only one species, ''Triceratops horridus''.<ref>Ostrom, J. H., and Wellnhofer, P. (1986). The Munich specimen of ''Triceratops'' with a revision of the genus. ''Zitteliana'' '''14''':111–158.</ref> Part of their rationale was that generally there are only one or two species of any large animal in a region (modern examples being the [[African elephant|elephant]] and the [[giraffe]] in modern Africa). To their findings, Lehman added the old Lull-Sternberg lineages combined with maturity and [[sexual dimorphism]], suggesting that the ''T. horridus''-''T. prorsus''-''T. brevicornus'' lineage was composed of females, the ''T.calicornis''-''T.elatus'' lineage was made up of males, and the ''T. obtusus''-''T. hatcheri'' lineage was of [[pathology|pathologic]] old males.<ref name="TML90"/> His reasoning was that males had taller, more erect horns and larger skulls, and females had smaller skulls with shorter, forward-facing horns.
These findings, however, were contested a few years later by Catherine Forster, who 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 ''[[Diceratus]]'') ''hatcheri'' differed enough to warrant a separate genus.<ref>Forster, C.A. (1996). Species resolution in ''Triceratops'': cladistic and morphometric approaches. ''Journal of Vertebrate Paleontology'' '''16'''(2):259–270.</ref> She found that ''T. horridus'' and several other species belonged together, and ''T. prorsus'' and ''T. brevicornus'' stood alone, and since there were many more specimens in the first group, she suggested that this meant the two groups were two species. It is still possible to interpret this reasoning as describing a single species with sexual dimorphism.<ref name="Dodhorned"/><ref name="TML98">Lehman, T. M. (1998). A gigantic skull and skeleton of the horned dinosaur ''Pentaceratops sternbergi'' from New Mexico. ''Journal of Paleontology'' '''72'''(5):894–906.</ref>
===Valid species===
[[Image:Triceratops 2 Skulls Senckenberg.jpg|thumb|Skulls of ''Triceratops prorsus'' in the Senckenberg Museum.]]
*''T. horridus'' <small>(Marsh, 1889) (originally ''[[Ceratops]]'')</small> ([[type species]])
*''T. prorsus'' <small>(Marsh, 1890)</small>
===Doubtful species===
The following species are considered ''[[nomen dubium|nomina dubia]]'' ("dubious names"), and are based on remains that are too poor or incomplete to be distinguished from pre-existing ''Triceratops'' species.
*''T. albertensis'' <small>([[Charles Mortram Sternberg|C. M. Sternberg]], 1949)</small>
*''T. alticornis'' <small>([[Othniel Charles Marsh|Marsh]], 1887 (originally ''[[Bison]]''))</small>
*''T. eurycephalus'' <small>([[Erich Maren Schlaikjer|Schlaikjer]], 1935)</small>
*''T. galeus'' <small>(Marsh, 1889)</small>
*''T. ingens'' <small>([[R. S. Lull|Lull]], 1915)</small>
*''T. maximus'' <small>([[Barnum Brown|Brown]], 1933)</small>
*''T. sulcatus'' <small>(Marsh, 1890)</small>
===Misassignments===
*''T. brevicornus'' <small>(Hatcher, 1905)</small> (=''T. prorsus'')
*''T. calicornus'' <small>(Marsh, 1898)</small> (=''T. horridus'')
*''T. elatus'' <small>(Marsh, 1891)</small> (=''T. horridus'')
*''T. flabellatus'' <small>(Marsh, 1889)</small> (=''T. horridus'')
*''T. hatcheri'' <small>(Lull, 1907)</small> (=''Diceratus hatcheri'')
*''T. mortuarius'' <small>([[Edward Drinker Cope|Cope]], 1874)</small> (''nomen dubium''; originally ''[[Polyonax]]''; =''Polyonax mortuarius'')
*''T. obtusus'' <small>(Marsh, 1898)</small> (=''T. horridus'')
*''T. serratus'' <small>(Marsh, 1890)</small> (=''T. horridus'')
*''T. sylvestris'' <small>(Cope, 1872)</small> (''nomen dubium''; originally ''[[Agathaumas]] sylvestris'')
==Paleobiology==
[[Image:Pasta - triceratops brain.jpg|thumb|A 1905 chart showing the relatively small brain of a ''Triceratops'' (top).]]
Although ''Triceratops'' are commonly portrayed as [[herd]]ing animals, there is currently no solid evidence that they 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.<ref name="Dodhorned"/> However, these remains are very common; for example, [[Bruce Erickson (paleontologist)|Bruce Erickson]], a paleontologist of the [[Science Museum of Minnesota]], has reported having seen 200 specimens of ''T. prorsus'' in the [[Hell Creek Formation]] of [[Montana]].<ref>Erickson, B.R. (1966). Mounted skeleton of ''Triceratops prorsus'' in the Science Museum. ''Scientific Publications of the Science Museum'' '''1''':1–16.</ref> Similarly, [[Barnum Brown]] claimed to have seen over 500 skulls in the field.<ref>Dodson, P. (1996). ''The Horned Dinosaurs''. Princeton University Press:Princeton, New Jersey, p. 79. ISBN 0-691-02882-6.</ref> Because ''Triceratops'' teeth, horn fragments, frill fragments, and other skull fragments are such abundant fossils in the [[Lance Formation|Lancian faunal stage]] of the late [[Maastrichtian]] ([[late Cretaceous]], 68 to 65 mya) Period of western North America, it is regarded as among the dominant herbivores of the time, if not the most dominant herbivore. In 1986, [[Robert Bakker]] estimated it as making up 5/6ths of the large dinosaur fauna at the end of the Cretaceous.<ref name=RTB86a>Bakker, R.T. (1986). ''The Dinosaur Heresies: New Theories Unlocking The Mystery of the Dinosaurs and Their Extinction'' William Morrow:New York, p. 438. ISBN 0140100555.</ref> Unlike most animals, skull fossils are far more common than [[postcrania]]l bones for ''Triceratops'', suggesting that the skull had an unusually high preservation potential.<ref name=KD94>{{cite book |last=Derstler |first=Kraig |year=1994 |editor=Nelson, Gerald E. (ed.) |title=The Dinosaurs of Wyoming |series=Wyoming Geological Association Guidebook, 44th Annual Field Conference |chapter=Dinosaurs of the Lance Formation in eastern Wyoming |publisher=Wyoming Geological Association |pages=127-146}}</ref>
''Triceratops'' was one of the last ceratopsian genera to appear before the [[Cretaceous-Tertiary extinction event]]. The related ''[[Diceratus]]'' and ''[[Torosaurus]]'', and the more distantly related diminutive ''[[Leptoceratops]]'', were also present, though their remains have been rarely encountered.<ref name="Dodhorned"/>
===Dentition and diet===
''Triceratops'' were [[herbivore|herbivorous]], and because of their low head, their primary food was probably low growth, although they may have been able to knock down taller [[plant]]s with their horns, [[beak]], and bulk.<ref>Tait J., and Brown, B. (1928). How the Ceratopsia carried and used their head. ''Transactions of the Royal Society of Canada.'' '''22''':13–23.</ref><ref name ="Dino2"/> The [[jaw]]s were tipped with a deep, narrow beak, believed to have been better at grasping and plucking than biting.<ref name="Ostrom66">{{cite journal|author=Ostrom, J. H.|date=1966| title=Functional morphology and evolution of the ceratopsian dinosaurs| journal=[[Evolution (journal)|Evolution]]| volume=20| issue=3 | pages = 290| doi=10.2307/2406631}}</ref>
''Triceratops'' [[tooth|teeth]] were arranged in groups called batteries, of 36 to 40 tooth columns, in each side of each jaw with 3 to 5 stacked teeth per column, depending on the size of the animal.<ref name="Dino2"/> This gives a range of 432 to 800 teeth, of which only a fraction were in use at any given time (tooth replacement was continuous and occurred throughout the life of the animal).<ref name ="Dino2"/> They functioned by shearing in a vertical to near-vertical orientation.<ref name="Dino2"/> The great size and numerous teeth of ''Triceratops'' suggests that they ate large volumes of fibrous plant material,<ref name ="Dino2"/> with some suggesting [[Arecaceae|palms]] and [[cycad]]s,<ref>Ostrom, J. H. (1964). A functional analysis of jaw mechanics in the dinosaur ''Triceratops''. ''Postilla'', Yale Peabody Museum '''88''':1–35.</ref><ref>Weishampel, D. B. (1984). Evolution of jaw mechanisms in ornithopod dinosaurs. ''Advances in Anatomy, Embryology, and Cell Biology'' '''87''':1–110.</ref> and others suggesting [[fern]]s, which then grew in prairies.<ref>Coe, M. J., Dilcher, D. L., Farlow, J. O., Jarzen, D. M., and Russell, D. A. (1987). Dinosaurs and land plants. In: Friis, E. M., Chaloner, W. G., and Crane, P. R. (eds.) ''The Origins of Angiosperms and their Biological Consequences'' Cambridge University Press, pp. 225–258. ISBN 0-521-32357-6.</ref>
===Functions of the horns and frill===
[[Image:Triceratops 1.jpg|thumb|''Triceratops'' head from the front]]
[[Image:Triceratops 2.jpg|thumb|''Triceratops'' head from the side]]
There has been much speculation over the functions of ''Triceratops''' head adornments. The two main theories have revolved around use in combat, or display in courtship, with the latter thought now to be the most likely primary function.<ref name="Dino2"/>
Early on, Lull postulated that the frills may have served as anchor points for the jaw muscles to aid chewing by allowing increased size and thus power for the muscles.<ref>Lull, R. S. (1908). The cranial musculature and the origin of the frill in the ceratopsian dinosaurs. ''American Journal of Science'' 4(25):387–399.</ref> This has been put forward by other authors over the years, but later studies do not find evidence of large muscle attachments on the frill bones.<ref name = "Forster90">Forster, C. A. (1990). The cranial morphology and systematics of ''Triceratops'', with a preliminary analysis of ceratopsian phylogeny. Ph.D. Dissertation. University of Pennsylvania, Philadelphia. 227 pp.</ref>
''Triceratops'' were long thought to have possibly used their horns and frills in combat with predators such as ''[[Tyrannosaurus]]'', the idea being discussed first by [[Charles Hazelius Sternberg|C. H. Sternberg]] in 1917 and 70 years later by Robert Bakker.<ref>Sternberg, C. H. (1917). ''Hunting Dinosaurs in the Badlands of the Red Deer River, Alberta, Canada''. Published by the author, San Diego, California, 261 pp.</ref><ref name=RTB86>Bakker, R. T. (1986). ''The Dinosaur Heresies: New Theories Unlocking The Mystery of the Dinosaurs and Their Extinction'' William Morrow:New York. ISBN 0140100555.</ref> There is evidence that ''Tyrannosaurus'' did prey upon them, as a ''Triceratops'' [[pelvis]] has been found with tyrannosaur toothmarks and subsequent healing, indicating the wound was made while the animal was alive.<ref name="fowler2006">Fowler, D. W., and Sullivan, R. M. (2006). A ceratopsid pelvis with toothmarks from the Upper Cretaceous Kirtland Formation, New Mexico: evidence of late Campanian tyrannosaurid feeding behavior. ''New Mexico Museum of Natural History and Science Bulletin'' '''35''':127–130.</ref>
In 2005, a [[BBC]] documentary, ''[[The Truth About Killer Dinosaurs]]'', tested how ''Triceratops'' might have defended themselves 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 [[kilometres per hour|km/h]] (15 [[miles per hour|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 themselves in this way—instead they probably stood their ground when attacked by large predators, using their horns for goring if the predator came close enough.
In addition to combat with predators using horns, ''Triceratops'' are classically shown engaging each other in combat with horns locked. While studies show that such activity would be feasible, if unlike that of present-day horned animals,<ref>Farke, A. A. (2004). Horn Use in ''Triceratops'' (Dinosauria: Ceratopsidae): Testing Behavioral Hypotheses Using Scale Models. ''Palaeo-electronica''.</ref> there is no evidence that they actually did so. Additionally, although pitting, holes, lesions, and other damage on ''Triceratops'' skulls (and the skulls of other ceratopsids) are often attributed to horn damage in combat, a recent study finds no evidence for horn thrust injuries causing these forms of damage (for example, there is no evidence of infection or healing). Instead, non-pathological [[bone resorption]], or unknown bone diseases, are suggested as causes.<ref name=TF06>Tanke, D. H, and Farke, A. A. (2006). Bone resorption, bone lesions, and extracranial fenestrae in ceratopsid dinosaurs: a preliminary assessment. in: Carpenter, K. (ed.). ''Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs'' Indiana University Press: Bloomington. pp. 319–347. ISBN 0-253-34817-X.</ref>
The large frill also may have helped to increase body area to [[thermoregulation|regulate body temperature]].<ref>{{cite journal|author=Wheeler, P.E.|date=1978|title=Elaborate CNS cooling structures in large dinosaurs|journal=[[Nature (journal)|Nature]]|issue=275|pages=441–443|doi=10.1038/275441a0 | volume = 275}}</ref> A similar theory has been proposed regarding the plates of ''[[Stegosaurus]]'',<ref>{{cite journal|author=Farlow, J. O., Thompson, C. V., and Rosner, D. E.|date=1976| title=Plates of the dinosaur ''Stegosaurus'': Forced convection heat loss fins?| journal=[[Science (magazine)|Science]]| volume=192 | pages = 1123| doi=10.1126/science.192.4244.1123| pmid=17748675}}</ref> although this use alone would not account for the bizarre and extravagant variation seen in different members of the [[Ceratopsidae]].<ref name="Dino2"/> This observation is highly suggestive of what is now believed to be the primary function, display.
[[Image:TriceratopsYoungAndAdultSkulls5994.JPG|left|thumb|Juvenile and adult skulls — the juvenile skull is about the size of an adult human head]]
The theory of their use in sexual display was first proposed by Davitashvili in 1961 and has gained increasing acceptance since.<ref name = "Davitashvili61">{{cite book|title=The Theory of sexual selection|year=1961|author=Davitashvili L|pages=p. 538|publisher=Izdatel'stvo Akademia nauk SSSR}}</ref><ref name="Forster90"/><ref name="TML90"/> Evidence that visual display was important, either in courtship or in other social behaviour, can be seen in the fact that horned dinosaurs differ markedly in their adornments, making each species highly distinctive. Also, modern living creatures with such displays of horns and adornments use them in similar behaviour.<ref>{{cite journal|author=Farlow, J. O., and Dodson, P.|date=1975|title=The behavioral significance of frill and horn morphology in ceratopsian dinosaurs|journal=[[Evolution (journal)|Evolution]]|volume=29|issue=2 | pages = 353|doi=10.2307/2407222}}</ref> A recent study of the smallest ''Triceratops'' skull, ascertained to be a juvenile, shows the frill and horns developed at a very early age, predating sexual development and thus probably important for visual communication and species recognition in general.<ref>{{cite journal|author=Goodwin, M. B., Clemens, W. A., Horner, J. R., and Padian, K.| date=2006| url=http://www.ucmp.berkeley.edu/people/mbg/Goodwin_et_al_2006.pdf| title=The smallest known ''Triceratops'' skull: new observations on ceratopsid cranial anatomy and ontogeny.| journal=Journal of Vertebrate Paleontology| volume=26| issue=1 | pages = 103 | doi = 10.1671/0272-4634(2006)26[103:TSKTSN]2.0.CO;2| year=2006}}</ref> The large eyes and shortened features, a hallmark of "cute" baby mammals, also suggest that the parent ''Triceratops'' may have cared for its young.
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==Depiction in recent popular media==
[[Image:Triceratops - 1904.jpg|left|thumb|1904 illustration by [[Charles R. Knight]]]]
The distinctive appearance of ''Triceratops'' has led to them being frequently depicted in films, computer games and documentaries. They appear in the film ''[[Jurassic Park (film)|Jurassic Park]]'', where one is portrayed as sick and is being treated by humans. They have also been featured in three major dinosaur documentaries: ''[[Walking with Dinosaurs]]'', ''[[The Truth About Killer Dinosaurs]]'' and'' [[Prehistoric Park]]''.
They are famously known as "three-horns" (and are so named in ''[[The Land Before Time]]'' [[animation|animated film]] and its numerous sequels) due to the three prominent horns on their head and nose, which have become almost synonymous with the dinosaurs. The shorthand "Trike" is another common informal name, and is also the name of the ''Triceratops'' character in the [[children's literature|children's book]] series and television [[animated cartoon|cartoon]] series ''[[Harry and His Bucket Full of Dinosaurs]]''. Other TV series include [[Slag (Transformers)| Slag]] of [[Slag_(Transformer)#Transformers:_Generation_1|Transformers]] fame, ''[[Dinosaucers]]'', ''[[Dino-Riders]]'' and ''[[Dinozaurs]]''. In the first series of [[Mighty Morphin' Power Rangers]], the blue ranger's robot, called a "zord", took the shape of a triceratops, and the ranger's helmet was fashioned after the animal.
[[Image:Scan00tri14.jpg|thumb|[[Animatronic]] juvenile ''Triceratops'', Experimentarium, [[Copenhagen]].]]
A recurring theme, especially in children's dinosaur books, is a climactic showdown or battle between ''Triceratops'' and ''T. rex''.<ref>Geis, D. (1982). ''How and Why Book of Dinosaurs.'' Allan Publishers. ISBN 0-824150015.</ref><ref>Watson, J. W. (1981). ''The Giant Golden Book of Dinosaurs.'' Random House Children's Books. ISBN 0-307137643.</ref><ref>Pistorius A. (1958) What dinosaur is it? Follett Pub. Co., Chicago.</ref><ref>Wise, W. (1963) In The Time of The Dinosaurs. Scholastic. ISBN 0-590323512.</ref> As such these two dinosaurs are often depicted and thought of as natural enemies. A memorable but anachronistic battle with ''[[Ceratosaurus]]'' substituting for ''T. rex'' is featured in the 1966 movie ''[[One Million Years B.C.]]''
''Triceratops'' appears in video games either derived directly from the ''Jurassic Park'' series or similarly themed, namely the 1997 PC games ''[[Jurassic Park: Chaos Island]]'' and ''[[Turok: Dinosaur Hunter]]'', and the 2000 PC and Playstation game ''[[Dino Crisis 2]]''. ''Triceratops'' also features in the ''[[Zoo Tycoon franchise|Zoo Tycoon]]'' franchise. As well, it is a popular creature used in games designed by [[Nintendo]], including ''[[Diddy Kong Racing]]'' and ''[[Starfox Adventures]]''. ''Triceratops'' (the species are not identified) is also the official [[state fossil]] of [[South Dakota]],<ref>{{cite web|author = State of South Dakota | title = Signs and Symbols of South Dakota..... | url=http://www.state.sd.us/state/sdsym.htm | accessdate = 2007-01-20}}</ref> and the official state dinosaur of [[Wyoming]].<ref>{{cite web | author = State of Wyoming | title = State of Wyoming - General Information | url= http://wyoming.gov/general/general.asp | accessdate = 2007-01-20 }}</ref>
==References==
{{reflist|2}}
==External links==
{{Spoken Wikipedia|En-Triceratops.ogg|2007-03-19}}
{{commons|Triceratops}}
{{Wikibooks|Wikijunior Dinosaurs/Triceratops}}
{{Wikispecies}}
*[http://www.nhm.ac.uk/jdsml/nature-online/dino-directory/detail.dsml?Genus=Triceratops ''Triceratops'' in the Dino Directory]
*[http://www.cbv.ns.ca/marigold/history/dinosaurs/datafiles/triceratops.html ''Triceratops''] (short summary and good color illustration)
*[http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Triceratops.shtml ''Triceratops'' For Kids] (a fact sheet about the ''Triceratops'' with activities for kids)
*[http://www.mnh.si.edu/exhibits/triceratops/index.html Smithsonian Exhibit]
*[http://dml.cmnh.org/2002Jul/msg00898.html Dinosaur Mailing List post on ''Triceratops'' stance]
*[http://www.archive.org/details/en.wikipedia.org_wiki_Triceratops_2007_March_19 Listen to this article, ''Triceratops'' at the Internet Archive]
{{featured article}}
{{portalpar|Dinosaurs}}
[[Category:Ceratopsians]]
[[Category:Cretaceous dinosaurs]]
[[Category:Dinosaurs of North America]]
[[Category:Symbols of South Dakota]]
[[Category:Symbols of Wyoming]]
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