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Triceratops (pronounced /traɪˈsɛrətɒps/) is an extinct genus of herbivorous ceratopsid dinosaur which lived during the late Maastrichtian stage of the Late Cretaceous Period, around 68 to 66 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.[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 upon by the fearsome Tyrannosaurus,[2][3] it is unclear whether the two battled the way they are commonly depicted in movies, children's dinosaur books and many cartoons. The fossil can be found in the United States.

A complete Triceratops skeleton has yet to be found;[4] however, the animal is well-known from numerous 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 best-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.

Description[]

Triceratops size vs

Triceratops compared in size with a human.

Individual Triceratops are estimated to have reached about 7.9 to 9.0 m (26.0–29.5 ft) in length, 2.9 to 3.0 m (9.5–9.8 ft) in height,[6][7] and 6.1–12.0 tonnes (13,000-26,000 lb) in weight.[8] 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,[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 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.

The skin of Triceratops was unusual compared to other dinosaurs. Skin impressions from an as-yet undescribed specimen show that some species may have been covered in bristle-like structures, similar to the more primitive ceratopsian Psittacosaurus.

Limbs[]

Trike skeleton

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.[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 (as in the modern rhinoceros).[10][11] This conclusion does not preclude a sprawling gait for confrontations or feeding.

The hands and forearms of Triceratops retained a fairly primitive structure compared to other quadrupedal dinosaurs such as thyreophorans and many sauropods. In those two groups, the forelimbs of quadrupedal species were usually rotated so that the hands faced forward with palms backward ("pronated") as the animals walked. Triceratops, like other ceratopsians and the related quadrupedal ornithopods, walked with most of their fingers pointing out and away from the body, the primitive condition for dinosaurs also retained by bipedal forms like the theropods. In Triceratops, the weight of the body was carried by only the first three fingers of the hand, while digits 4 and 5 were vestigial and lacked claws or hooves. The phalangeal formula is 2-3-4-3-1, meaning that the innermost finger of the forelimb has two bones, the next has three, etc.

Classification[]

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 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.[12] Later revisions supported this view, formally describing the first, short-frilled group as Centrosaurinae (including Triceratops), and the second, long-frilled group as Chasmosaurinae.[13][14]

Triceratops-life restoration

Life restoration of Triceratops horridus.

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.

An imposing Triceratops fossil on display, lit by blue and yellow light.

'Horridus', the most complete Triceratops fossil known, on display at the Melbourne Museum.

Below is a cladogram following Sampson et al. (2010).

Ceratopsidae

Centrosaurinae


Chasmosaurinae

Chasmosaurus




Mojoceratops




Agujaceratops





Utahceratops



Pentaceratops





Coahuilaceratops





Kosmoceratops



Vagaceratops





Anchiceratops




Arrhinoceratops




Ojoceratops



Eotriceratops




Torosaurus




Nedoceratops



Triceratops















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 (i.e. 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]

Origins[]

Laramie Triceratops skull

Skull of Triceratops from the Laramie Formation of eastern Colorado. Based on the age of the Laramie Formation, it may be the oldest Triceratops 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,[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 Ceratopsinae subfamily, a likely ancestor may have resembled Chasmosaurus, which thrived some 5 million years earlier.

History[]

Etymology[]

The term Triceratops, which literally means "three-horned face", is derived from the Greek tri/τρι- meaning "three", ceras/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 and South Dakota (in addition to Colorado and Wyoming), and 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 (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.[5] Discoverers would name these as separate species (listed below), and came up with several phylogenetic schemes for how they were related to each other.

Triceratops prorsus

Triceratops prorsus skeleton at the Science Museum of Minnesota.

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.[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.

Triceratops AMNH 01

Triceratops horridus skeleton at the American Museum of Natural History, in New York City.

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[]

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.

Misassignments[]

  • 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)

Paleobiology[]

Tyrannosaurus and Triceratops at Natural History Museum of Los Angeles County

A Triceratops mounted next to a Tyrannosaurus at the Los Angeles Natural History Museum

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, there is currently only one documented bonebed dominated by Triceratops bones: a site in southeastern Montana with the remains of three juveniles. It may be significant that only juveniles were present. In 2012, a group of three Triceratops in relatively complete condition, each of varying sizes from a full-grown adult to a small juvenile, were found near Newcastle, Wyoming. The remains are currently under excavation by paleontologist Peter Larson and a team from the Black Hills Institute. It is believed that the animals were traveling as a family unit, but it remains unknown if the group consists of a mated pair and their offspring, or two females and a juvenile they were caring for. The remains also show signs of predation or scavenging from Tyrannosaurus, particularly on the largest specimen, with the bones of the front limbs showing breakage and puncture wounds from Tyrannosaurus teeth. In 2020, Illies and Fowler described the co-ossified distal caudal vertebrae of Triceratops. According to them, this pathology could have arisen after one Triceratops accidentally stepped on the tail of another member of the herd.

Triceratops sp

Triceratops rib with theropod tooth marks at the middle

For many years, 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]

Analysis of the endocranial anatomy of Triceratops suggest its sense of smell was poor compared to that of other dinosaurs. Its ears were attuned to low frequency sounds, given the short cochlear lengths recorded in an analysis by Sakagami et al,. This same study also suggests that Triceratops held its head about 45 degrees to the ground, an angle which would showcase the horns and frill most effectively that simultaneously allowed the animal to take advantage of food through grazing.

A 2022 study by Wiemann and colleagues of various dinosaur genera, including Triceratops, suggests that it had an ectothermic (cold blooded) or gigantothermic metabolism, on par with that of modern reptiles. This was uncovered using the spectroscopy of lipoxidation signals, which are byproducts of oxidative phosphorylation and correlate with metabolic rates. They suggested that such metabolisms may have been common for ornithischian dinosaurs in general, with the group evolving towards ectothermy from an ancestor with an endothermic (warm blooded) metabolism.

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.[5]

Dentition and diet[]

Tric1

Close up of the jaws and teeth

Triceratops were herbivorous, and because of their low head, their primary food was probably low growth, although they may have been able to knock down taller plants with their horns, beak, and bulk.[9][37] The jaws were tipped with a deep, narrow beak, believed to have been better at grasping and plucking than biting.[38]

Triceratops 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.[9] 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).[9] They functioned by shearing in a vertical to near-vertical orientation.[9] The great size and numerous teeth of Triceratops suggests that they ate large volumes of fibrous plant material,[9] with some suggesting palms and cyads [39][40] and others suggesting ferns, which then grew in prairies.[41]

Functions of the horns and frill[]

Triceratops skull frills

Triceratops skull with prominent row of epoccipitals along its frill.

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.[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.[42] 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.[43]

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.[44][45] 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.[46] 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 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 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 lesions

Examples of periosteal reactive bone in selected specimens of Triceratops.

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,[47] 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.[48] 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.[49] The frequency of injury was found to be 14% in Triceratops. The researchers also concluded that the damage found on the specimens in the study was often too localized to be caused by bone disease.Histological examination reveals that the frill of Triceratops is composed of fibrolamellar bone. This contains fibroblasts that play a critical role in wound healing and is capable of rapidly depositing bone during remodeling.

One skull was found with a hole in the jugal bone, apparently a puncture wound sustained while the animal was alive, as indicated by signs of healing. The hole has a diameter close to that of the distal end of a Triceratops horn. This and other apparent healed wounds in the skulls of ceratopsians has been cited as evidence of non-fatal intraspecific competition in these dinosaurs. Another specimen, referred to as "Big John", has a similar fenestra to the squamosal caused by what appears to be another Triceratops horn and the squamosal bone shows signs of significant healing, further vindicating the hypothesis that this ceratopsian used its horns for intra-specific combat.

The large frill also may have helped to increase body area to regulate body temperature.[50] A similar theory has been proposed regarding the plates of Stegosaurus,[51] 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.

Trike adult and baby

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.[18][43][52] 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.[53] 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.[54] The large eyes and shortened features, a hallmark of "cute" baby mammals, also suggest that the parent Triceratops may have cared for its young. The use of the exaggerated structures to enable dinosaurs to recognize their own species has been questioned, as no such function exists for such structures in modern species.

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 ontogeny

Skull growth series

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.

Torosaurus as growth stage of Triceratops[]

Main article: Torosaurus

Torosaurus is a ceratopsid genus first identified from a pair of skulls in 1891, two years after the identification of Triceratops by Othneil Charles Marsh. The genus Torosaurus resembles Triceratops in geological age, distribution, anatomy, and size, so it has been recognised as a close relative. Its distinguishing features are an elongated skull and the presence of two ovular fenestrae in the frill. Paleontologists investigating dinosaur ontogeny in Montana's Hell Creek Formation have recently presented evidence that the two represent a single genus.

Torosaurus and Triceratops

A, Triceratops prorsus holotype YPM 1822 and B, Torosaurus latus ANSP 15192

John Scannella, in a paper presented in Bristol at the conference of the Society of Vertebrate Paleontology (September 25, 2009), reclassified Torosaurus as especially mature Triceratops individuals, perhaps representing a single sex. Horner, Scannella's mentor at Bozeman Campus, Montana State University, noted that ceratopsian skulls consist of metaplastic bone. A characteristic of metaplastic bone is that it lengthens and shortens over time, extending and resorbing to form new shapes. Significant variety is seen even in those skulls already identified as Triceratops, Horner said, "where the horn orientation is backwards in juveniles and forward in adults". Approximately 50% of all subadult Triceratops skulls have two thin areas in the frill that correspond with the placement of "holes" in Torosaurus skulls, suggesting that holes developed to offset the weight that would otherwise have been added as maturing Triceratops individuals grew longer frills. A paper describing these findings in detail was published in July 2010 by Scannella and Horner. It formally argues that Torosaurus and the similar contemporary Nedoceratops are synonymous with Triceratops.

The assertion has since ignited much debate. Andrew Farke had, in 2006, stressed that no systematic differences could be found between Torosaurus and Triceratops, apart from the frill. He nevertheless disputed Scannella's conclusion by arguing in 2011 that the proposed morphological changes required to "age" a Triceratops into a Torosaurus would be without precedent among ceratopsids. Such changes would include the growth of additional epoccipitals, reversion of bone texture from an adult to immature type and back to adult again, and growth of frill holes at a later stage than usual. A study by Nicholas Longrich and Daniel Field analyzed 35 specimens of both Triceratops and Torosaurus. The authors concluded that Triceratopsindividuals too old to be considered immature forms are represented in the fossil record, as are Torosaurus individuals too young to be considered fully mature adults. The synonymy of Triceratops and Torosaurus cannot be supported, they said, without more convincing intermediate forms than Scannella and Horner initially produced. Scannella's Triceratops specimen with a hole on its frill, they argued, could represent a diseased or malformed individual rather than a transitional stage between an immature Triceratops and mature Torosaurus form.

Other genera as growth stages of Triceratops[]

Main article: Nedoceratops

Nedoceratops skull, PLoS ONE

Comparisons between the skulls of Triceratops and Nedoceratops

Opinion has varied on the validity of a separate genus for Nedoceratops. Scannella and Horner regarded it as an intermediate growth stage between Triceratops and Torosaurus. Farke, in his 2011 redescription of the only known skull, concluded that it was an aged individual of its own valid taxon, Nedoceratops hatcheri. Longrich and Fields also did not consider it a transition between Torosaurus and Triceratops, suggesting that the frill holes were pathological.

As described above, Scannella had argued in 2010 that Nedoceratops should be considered a synonym of Triceratops. Farke (2011) maintained that it represents a valid distinct genus. Longrich agreed with Scannella about Nedoceratops and made a further suggestion that the recently described Ojoceratops was likewise a synonym. The fossils, he argued, are indistinguishable from the Triceratops horridus specimens that were previously attributed to the defunct species Triceratops serratus.

Longrich observed that another newly described genus, Tatankaceratops, displayed a strange mix of characteristics already found in adult and juvenile Triceratops. Rather than representing a distinct genus, Tatankaceratopscould as easily represent a dwarf Triceratopsor a Triceratops individual with a developmental disorder that caused it to stop growing prematurely.

Paleoecology[]

Upper Cretaceous Hell Creek dinosaur census

Pie chart of the time averaged census for large-bodied dinosaurs from the entire Hell Creek Formation in the study area

Triceratops lived in North America, all fossils dating to before the K-PG mass extinction. Fossils are excavated in the Hell Creek, Laramie, Denver, Scollard, Lance and Evanston Formations, all in layers containing Maastrichtian-aged deposits. The Hell Creek Formation is among the most well-known of Triceratops fossils.

Hell Creek dinosaurs and pterosaurs by durbed

Triceratops and other animals of the Hell Creek Formation

The Triceratops would have traveled as a large herd. Whenever predators would have attacked the herd, it has been theorized that the healthy adults would form a ring, and the young and weak members would go into the center of the ring. This formation would form a trough wall of horns, making it virtually impossible for the predators to pick off any member of the herd. Triceratops was preyed upon by a diverse array of predators. Juveniles would have been suitable prey for the large dromaeosaur Dakotaraptor, and full grown individuals a challenging meal for massive predators like Tyrannosaurus. Both species are found from Hell Creek, T. horridus, T. prorsus and a transitional species from the middle layers. Small theropods like Acheroraptor and caenagnathids, with large ornithomimids, hadrosaurs like Edmontosaurus, a vast array of fishes and crocodilians. Parts of Hell Creek overlooked the Western Interior Seaway and parts of the Fox Hills Formation.

Cultural Influence[]

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, where one is portrayed as sick and is being treated by humans. More active Triceratops are also seen in the film's two sequels. 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 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 book series and television cartoon series Harry and His Bucket Full of Dinosaurs. The character "Baby Bop" from Barney & Friends is another example of a Triceratops in popular media.

A recurring theme, especially in children's dinosaur books, is a climactic showdown or battle between Triceratops and T. rex.[55][56][57][58] 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. As well, it is a popular creature used in games designed by Rareware, including Diddy Kong Racing and Starfox Adventures. Triceratops (the species are not identified) is also the official state fossil of South Dakota,[59] and the official state dinosaur of Wyoming.[60]

There is also a Japanese rock band called Toraiseratoppusu, which translates into English as Triceratops.


Trivia:[]

  • There is a theory that wasn't confirmed that Triceratops are actually teenagers Torosaurus.

JPInstitute.com Description[]

One of the top three on everyone's favorite dinosaur list, Triceratops is a very common dinosaur which lived at the very end of the Age of Dinosaurs. It had a huge frilled head with horns over each eye that could reach over 3 feet long. Triceratops had a third, smaller horn on its nose. These would be fearsome weapons against a predator.

Triceratops is one of the most common dinosaur fossils found. More than 50 skulls have been found. Within the genus, at least 7 species have been identified. The ceratopsian family is one of the most successful and varied of the Late Cretaceous. Triceratops is the largest member of this family, reaching the size of a school bus.

Triceratops was a herd animal; it is believed that large groups roamed North America. Their large, horny beaks and long rows of teeth were well designed for chewing the tough, low growing plants of the Late Cretaceous. It was likely the main predator of these animals was T. rex. A number of skeletons show bite and chew marks that match the teeth of T. rex. Horns and frills seemed to vary among individuals within the species. Some frills were very broad, others narrow. The nasal horn shows the most variance among individual specimens, no two being the same. The material that covered its horns in life would have added significantly to the length of the fossilized bone.


Dinosaur Field Guide Description[]

Triceratops ("three-horned face") may hold the record for holding records! It has the largest skull (tied with Torosaurus at 10 feet/3 m) and longest hip bone (4 feet/1.2 m) of any dinosaur, the strongest jaw of any land dwelling herbivore (or plant-eater that's ever lived, and the largest teeth of any herbivorous dinosaur. It was also the second most famous dinosaur, after Tyrannosaurus, for over a century; the first big dinosaur mounted at the Smithsonian Institution; and the first fully restored horned dinosaur (family Ceratopsidae). With its parrot-like beak, self-sharpening and ever-replacing teeth with muscles, 3-foot (I m) horns, and body more powerful than a rhino, Triceratops was the only dinosaur that could (and sometimes did) outfight a T. rex!

Fun Facts[]

One scientist assumed the first Triceratops specimen belonged to a bison.

Trivia[]

In 1999, Triceratops became the world's first fully "digital dinosaur." The Smithsonian's complete mounted skeleton- as well as each individual bone--was scanned into a computer and made available on their Web site, where you can move its individual bones.

Gallery[]

Appearance in Jurassic Park and other media[]

Jurassic Park[]

Triceratops appeared in all five 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.


The Land Before Time[]

The most notable Triceratops in the series are Cera, one of the main characters, Topps, Cera's father, Tria, her stepmother, and Tricia, her half-sister. Other Triceratops throughout the franchise include Cera's mother, full siblings, and her niece and nephew, Dinah and Dana. There are many background characters who are Triceratops.


We're Back! A Dinosaur's Story[]


Links[]

References[]

https://en.wikipedia.org/wiki/Triceratops

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