Total anky death
Extinct as can be!

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Temporal range: Late Cretaceous
Art reconstruction of Larry the Triceratops
A restoration of Larry the Triceratops
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Ornithischia
Suborder: Ceratopsia
Family: Ceratopsidae
Subfamily: Chasmosaurinae
Tribe: Triceratopsini
Genus: Triceratops
Marsh, 1889
Type species
Triceratops horridus
Marsh, 1889
Referred species
  • Triceratops horridus
    (Marsh, 1889)
  • Triceratops prorsus
    (Marsh, 1890)

Triceratops (meaning Three-horned face) is an extinct genus of herbivorous ceratopsid dinosaur which lived during the late Maastrichtian stage of the Late Cretaceous Period, around 68 to 66.038 million years ago (mya) in what is now United States and Canada. Fossils seem to be most common in Montana,Wyoming, United States and Saskatchewan, Canada. It was one of the last dinosaur genera to appear before the great K-Pg Extinction event.[1] Bearing a large bony frill and three horns on its large four-legged body, and conjuring similarities with the modern rhinoceros, Triceratops is one of the most recognizable of all dinosaurs. Although it shared the landscape with and was preyed by the mighty Tyrannosaurus[2][3]. It is unclear how did the two battle, but their rivalry are commonly depicted in movies, children's dinosaur books and many cartoons.

A complete Triceratops skeleton has yet to be found;[4] however, the animal is well-known from many partial remains 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 courtship and dominance displays, much like the antlers and horns of modern reindeer, mountain goats, or rhinoceros beetles.[5]

Triceratops is the most well-known of the ceratopsids, though the genus's exact placement within the group has been a point of contention amongst paleontologists. Two species, T. horridus and T. prorsus, are considered valid, although many other species have been named by many paleontologists.

Triceratops horridus and prorsus size comparison

Size comparison of T. horridus and T. prorsus


Triceratopses are estimated to have reached about 7.9 to 9.0 meters (25.9–29.5 feet) in length, 2.9 to 3.0 meters (9.5–9.8 feet) in height,[6][7] and 6.1–12.0 tonnes (13,000-26,000 lbs) in weight.[8] The most distinctive feature is their large skull. It could grow to be over 2 meters (7 feet) in length,[5] and could reach almost a third of the length of the entire animal.[4] It bore a single horn on the snout, above the nostrils, and a pair of horns approximately 1 meters (3 feet) 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. Triceratops species possessed a sturdy build, with strong limbs and short five-hoofed hands and four-hoofed feet.[9] Although certainly quadrupedal, 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.[5] This stance can be seen in paintings by Charles Knight and Rudolph Zallinger. However, ichnological evidence in the form of trackways 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.[10][11] This conclusion does not preclude a sprawling gait for confrontations or feeding.


Triceratops is the best known genus of the Ceratopsidae, a family of large North American 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, also known as Chasmosaurine). 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.[12] Later revisions supported this view, formally describing the first, short-frilled group as Centrosaurinae (including Triceratops), and the second, long-frilled group as Chasmosaurine.[13][14]

In 1949, 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.[15] However, he was largely ignored with John Ostrom,[16] and later David Norman, both placing Triceratops within Centrosaurinae.[17]

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.[18] Further research by Peter Dodson, including a 1990 cladistic analysis[19] and a 1993 study using RFTRA (Resistant-Fit Theta-Rho Analysis),[20] a morphometric technique which systematically measures similarities in skull shape, reinforces Triceratops placement in the ceratopsine subfamily.

Use in phylogenetics[]

In 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 Neornithes (for example, modern birds).[21] Furthermore, the bird-hipped dinosaurs, Ornithischia, have been designated as all dinosaurs with a more recent common ancestor to Triceratops than modern birds.[22]



Life restoration with curved long horns

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,[23] 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 Asian origin in the Jurassic, and the appearance of truly horned ceratopsians by the beginning of the late Cretaceous in North America.[9] As Triceratops is increasingly shown to be a member of the long-frilled Ceratopsidae subfamily, a likely ancestor may have resembled Chasmosaurus, which thrived some 5 million years earlier.



The term Triceratops, which literally means "three-horned face", is derived from the Greek tri/τρι- meaning "three", kéras/κέρας meaning "horn", and -ops/ωψ meaning "face".[24]

Discoveries and species[]

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.[25] This specimen was sent to Othniel Charles Marsh, who believed that the 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.[25][26] He realized that there were horned dinosaurs by the next year, which saw his publication of the genus Ceratops from fragmentary remains,[27] 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.[28] After reflection, however, Marsh changed his mind and gave it the generic name Triceratops, accepting his Bison alticornis as another species of Ceratops[29] (it would later be added to Triceratops[12]). 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 the American states of Montana, South Dakota, Colorado, and Wyoming. Additional fossils were found in the Canadian provinces of Saskatchewan and Alberta.

Number of species[]

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. 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.[5] Discoverers would name these as separate species, and came up with several 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. T. serratus and T. flabellatus stood apart from these groups.[12] 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.[14] 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.[14] 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.[15] This pattern was followed until the major studies of the 1980s and 1990s.

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.[30] Part of their rationale was that generally there are only three to four species of any large animal in a region (modern examples being the elephant, giraffe, rhinoceros, and hippopotamus 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 pathologic old males.[18] 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. hatcheri (now Nedoceratops) differed enough to warrant a separate genus.[31] 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.[5][32]

Valid species[]

  • T. horridus (Marsh, 1889) (originally Ceratops) (type species)
  • T. prorsus (Marsh, 1890)

Doubtful species[]

The following species are considered 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 (C. M. 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)


  • T. brevicornus (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) (=Diceratus hatcheri)
  • T. mortuarius (Cope, 1874) (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 sylvestris)


Although Triceratops are commonly portrayed as herding 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.[5] However, these remains are very common; for example, 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.[33] Similarly, Barnum Brown claimed to have seen over 500 skulls in the field.[34] Because Triceratops teeth, horn fragments, frill fragments, and other skull fragments are such abundant fossils in the 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.[35] Unlike most animals, skull fossils are far more common than postcranial bones for Triceratops, suggesting that the skull had an unusually high preservation potential.[36] New evidence presented in 2020 by Illies and Fowler etal., suggests that Triceratops lived in small groups of perhaps between five to ten individuals based on fossils collected in the previous decade.

Triceratops was one of the last ceratopsian genera to appear before the Cretaceous-Paleogene extinction event. The related Diceratus and Torosaurus, and the more distantly related diminutive Leptoceratops, were also present, though their remains have been rarely encountered.[5]

Dentition and diet[]

Triceratops lived on a herbivorous diet, with its most common food probably being vegetation growing low to the ground. However, the ceratopsian might have been able to knock down much taller plants thanks to its bulk, horns and beak.

The teeth of Triceratops were arranged in several groups known as batteries, which were composed of 36 to 40 tooth columns. Each side of each jaw had 3 to 5 stacked teeth per column, although this depended on the animal's size. As a result, Triceratops would have had 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). These teeth were highly adapted for shearing in a vertical to near-vertical orientation. Due to the massive size of Triceratops and the amount of teeth it had, it is likely that it would have eaten a large amount of highly fibrous plant material, with some suggesting that palms and cyads were a part of its main diet. Others suggest that Triceratops commonly dined on ferns, which then grew in prairies.

Functions of the horns and frill[]

There has been much mystery surrounding the horns and frill of Triceratops. The most commonly accepted theories have suggested that the animal would have used these in combat and within courtship. The latter is now thought to be the most plausible primary function.[9]

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.[37] 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.[38]

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 C. H. Sternberg in 1917 and 70 years later by Robert Bakker.[39][40] There is evidence that Tyrannosaurus did have aggressive head-on encounters with Triceratops, based on partially-healed tyrannosaur tooth marks on a Triceratops brow horn and squamosal; the bitten horn is also broken, with new bone growth after the break. Which animal was the aggressor is not known.[41] Tyrannosaurus is also known to have fed on Triceratops. Evidence for this includes a heavily tooth-scored Triceratops ilium and sacrum.[3]

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 24km/h (15mph). 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.

Triceratops Horridus leading it's herd

Triceratops Horridus

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,[42] there is disagreement about whether 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.[43] However, a newer study compared incidence rates of skull lesions in Triceratops and Centrosaurus and showed that these were consistent with Triceratops using its horns in combat and the frill being adapted as a protective structure, while lower pathology rates in Centrosaurus may indicate visual rather than physical use of cranial ornamentation, or a form of combat focused on the body rather than the head.[44]

The large frill also may have helped to increase body area to regulate body temperature.[45] A similar theory has been proposed regarding the plates of Stegosaurus,[46] although this use alone would not account for the bizarre and extravagant variation seen in different members of the Ceratopsidae.[9] This observation is highly suggestive of what is now believed to be the primary function, display.

The theory of their use in sexual display was first proposed by Davitashvili in 1961 and has gained increasing acceptance since.[18][38][47] Evidence that visual display was important, either in courtship or in other social behavior, 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 behavior.[48] 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.[49] The large eyes and shortened features, a hallmark of "cute" baby mammals, also suggest that the parent Triceratops may have cared for its young.

Notable specimens[]

  • YPM 1820- The holotype that was collected in 1888 from the Lance Formation of Wyoming, USA, by fossil hunter John Bell Hatcher, yet Marsh initially described this specimen as another species of Ceratops. It is known from an incomplete skull, excluding the frill and lower jaws.
  • YPM 1871E- known from brow horn core that were erroneously attributed to "Bison alticornis".
  • "Yoshi's Trike" MOR 3027- a specimen of Triceratops sp. that is known from a complete skull, 12 dorsal vertebrae, 2 cervical, and 1 caudal, ribs, scapulae, coracoid, hip bones, both femurs, two tibias, and one fibula. It was recovered from the Hell Creek middle third Formation. Also has longest brow horns of any trike found.
  • AMNH 5116- A specimen of T. horridus .
  • "Big John"- The largest Triceratops horridus specimen known, is 26 ft (7.4 m) long, with a 8.59 ft (2.62 meter) skull. On October 21 in Paris this Triceratops specimen will be sold for over a million dollars to never be seen again.

Growth and ontogeny[]

Triceratops epoccipitals

Frills of subadult and adult Triceratops

In 2006, the first extensive ontogenetic study of Triceratops was published in the journal Proceedings of the Royal Society. The study, by John R. Horner and Mark Goodwin, found that individuals of Triceratops could be divided into four general ontogenetic groups, babies, juveniles, subadults, and adults. With a total number of 28 skulls studied, the youngest was only 38 cm (15 in) long. Ten of the 28 skulls could be placed in order in a growth series with one representing each age. Each of the four growth stages were found to have identifying features. Multiple ontogenetic trends were discovered, including the size reduction of the epoccipitals, development, and reorientation of postorbital horns, and hollowing out of the horns.

In The Media[]

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Triceratops as seen in Jurassic Park

  • Triceratops appeared in all 6 Jurassic Park movies. However, it only played an important role in the first film, where an individual is sick and has collapsed, leading the characters to try to figure out what's wrong with it. Unlike the originals, the adult clones have triangular epoccipitals around their frills but in real life, the triangular epoccipitals can only be found on young and juveniles. It also shows that it has jugal cheek horns instead of one cheek horn on each side of the head.
  • Triceratops is an enemy in Jurassic Park arcade games.
  • Triceratops appeared in the BBC documentary, The Truth About Killer Dinosaurs, tested how Triceratops would defend itself against large predators like Tyrannosaurus rex. To see if Triceratops could charge other dinosaurs like a rhinoceros, an artificial Triceratops skull was made and propelled into simulated T. rex skin at 24 km/h (15 mph). The brow horns penetrated the skin, but the blunt nose horn and beak could not, and the front of the skull broke. The program therefore concluded that it would have been impossible for Triceratops to defend itself in this way - instead, it probably stood its ground when attacked by large predators, using its horns if the predator came close enough.
  • Triceratops was seen in Dinosaur Hunting (XBOX) on Stage 9, where 3 Triceratops are tranquilized and rescued.
  • It appears in Disney's Fantasia during The Rite of Spring segment.
  • It appears in the Carnivores game series and Primal Prey.
  • There were several Triceratops from the TV series Dinosaurs.
  • Triceratops also appear in many silent cheap movies about dinosaurs and documentaries.
  • TRICERATOPS is the name of a Japanese Band.
  • Triceratops appeared in the movie Dinosaur Island (2002 film), where a mother Triceratops sees Leo stealing her eggs and began charging at him.
  • A popular children book named The Enormous Egg features a Triceratops.
  • In the 1980s cartoon, Dino-Riders, the Rulons used numerous Triceratops.
  • The Transformers characters of Slag, Slug, Snarl, Knockdown, Ironlunge, Thunderlips, Stockade, Triceradon, and Guiledart each turn into a Triceratops.
  • The shorthand "Trike" is another common informal name, and is also the name of the Triceratops character in the children's book series and television cartoon series Harry and His Bucket Full of Dinosaurs. Other TV series include Dinosaucers, Dino-Riders, and Dinozaurs.
  • A recurring theme, especially in children's dinosaur books, is a climactic showdown or battle between Triceratops and T. rex. 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 stars in the anime film Age of the Great Dinosaurs where one is befriended by the main characters (who traveled back in time) before sacrificing itself in vain to defeat the film's main antagonist, a Tyrannosaurus with a gouged out eye.
  • In the book You Are Umasou (along with the anime adaptations), Heart, a Tyrannosaurus raised by a Maiasaura, witnesses a Triceratops battle a pack of other tyrannosaurs. Triceratops makes many cameos later.
  • Triceratops was featured in the documentary Dinosaur Revolution, where a bull Triceratops battled and lost to a pair of Tyrannosaurus rex named Stumpy & Tinkerbelle, however it won against a single Tyrannosaurus named Jack Palance, a rival of Stumpy’s and Tinkerbelle’s.
  • It was featured in an episode of Primeval: New World.
  • Triceratops was featured in several episodes of the 2006 BBC documentary television series, Prehistoric Park. One young teenaged male that Nigel Marvin saved was named Theo. He was the first, though unexpected, arrival to arrive at the park.
  • Dinosaurs Decoded and Prehistoric Denver are two more documentaries this world-renowned dinosaur's been in.
  • Triceratops prorsus will appear in the game Saurian as a playable dinosaur.
  • Triceratops appearances in 2 episodes of the 4 part PBS documentary program The Dinosaurs! "Flesh on the Bones" & "The Death of the Dinosaurs". It also appeared on the final episode of the Six part PBS NATURE Program Triumph of Life as a Skeleton ghost next to a White Rhinoceros.
  • Triceratops becomes one of the playable Vivosaurs in Fossil Fighters series.
  • Triceratops appeared in the Rugrats where it was seen as a toy in the episode Toy Palace and Princess Angelica. It also made its appearance in the episode Reptar 2010 where it battles Tyrannosaurus rex.

    The Triceratops as it appears in Jurassic World: The Game

  • In the Teenage Mutant Ninja Turtles franchise and Mirage comics, an alien species called the Triceratons have made numerous appearances. The turtles have also encountered dinosaurs in some episodes of the television shows.
  • The Triceratops is one of the tameable creatures in ARK: Survival Evolved.
  • The Triceratops is one of the first creatures you get in Parkasaurus.
  • Triceratops made an appearance in the Roblox game called "Dinosaur Simulator." Defaulted to you as a free skin, along with Tyrannosaurus rex.
  • Triceratops makes an appearance in the roblox game Era of Terror and its remake. In the original, it was notorious for being able to one-shot T. rex and constantly being used to KoS (Kill on Sight), and ultimately a lot of players would avoid a triceratops as soon as they saw one, even if that particular one was docile. Fortunately in the remake it was nerfed and it now has much more even stats.
  • Recently, Triceratops made an appearance in both the BBC Documentary Series, Prehistoric Planet, in both seasons' fifth episodes, "Forests" and "North America", and, just recently, in the new Netflix Original Documentary Series, Life on Our Planet, where one female is hunted and chased by a mother Tyrannosaurus rex and her two offspring, but is defended by her herd.
  • Triceratops appears in Prehistoric Kingdom with skins for both species.
  • Triceratops is mentioned in When Dinosaurs Ruled.


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  2. 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.
  3. 3.0 3.1 Erickson, GM, and Olson, KH, in 1996. "Bite marks attributable to Tyrannosaurus rex: preliminary description and implications", from the Journal of Vertebrate Paleontology, vol. 16, issue 1, pages 175–178.
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  6. DinoDictionary.com :: T Dinosaurs Page 2
  7. Triceratops in The Natural History Museum's Dino Directory
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  10. Christiansen, P., and Paul, G.S. (2001). Limb bone scaling, limb proportions, and bone strength in neoceratopsian dinosaurs. Gaia 16:13–29.
  11. 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.
  12. 12.0 12.1 12.2 Hatcher, J. B., Marsh, O. C. and Lull, R. S. (1907) The Ceratopsia. Government Printing Office, Washington, D.C. ISBN 0405127138.
  13. 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.
  14. 14.0 14.1 14.2 Lull, R. S. (1933) A revision of the Ceratopsia or horned dinosaurs. Memoirs of the Peabody Museum of Natural History 3(3):1–175.
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